Onii-san's phone's notification sound rang as he was going down the station's stairs. He looked at it and sighed, annoyed. It was the department manager asking people for help on a new uninteresting and tiresome project. And once again, Onii-san would have to be in it, as always. But this bad news quickly vanished out of his brain as today was Monday and just like every other Mondays, he would get to see the most beautiful creature God has put in His wisdom on this hellish Earth. He promptly passed the turnstile to arrive on the platform. For once, there was not so many people waiting for the train and he quickly found her small figure from behind. He immediately noticed that the young girl was wearing the same pea coat she wore during Christmas. The businessman walked towards her, impatient to see his angel. Her smile, joy and beauty would easily give him enough energy to survive this week. That is all he needed to take on anything that would come on his way this week.

- Good morning, Ai-cha- !

His joyfully greeting stopped when he saw her face as she turned around. Ai-chan looked at him, upset and sollen, almost with an angry look. She was slightly slouching over, holding her breasts on both her forearms, letting all their weight rest on them. Somehow, this made easily her two mountains look even bigger for her coat to contain. Usually, a pea coat was a rather straight cloth, which greatly help cover the curves of its wearer. But in this situation, it was way too much for him, judging by the two enormous bulges bending the fabric. If she would have wore any other cloth, she would have been even stunning. After all, the last time they saw each other, didn't she strongly hinted that she grew a bit ? Onii-san giggled in his head with sparkles in his eyes, mesmerized again by the thought of the sheer massive size of his angel's ample bust.

- Good morning, she coldly replied with her teeth clenched and eyebrows frowned.

- Something happened ? asked Onii-san worried that she would be angry against him.

He felt a weight in his chest, fearing it would be the case. She looked away towards the train racks, her anxious gaze lost in the distance.

- Well, today is... a marathon, she said, sollen.

Having said the word, she retightened her hold on her mountains, making them even more bigger. Her peacock's wooden buttons were already stretching their small ropes to their maximum, judging by the tension.

- A school marathon ?

- In this day and age ? he simply asked, feeling like she wanted some support from him.

- So archaic, coldly replied Ai-chan before sighing. It's gonna hurt. It's definitely gonna hurt… she repeated to herself.

- Really ?

Onii-san understood now. Ai-chan's bosom was so huge that the bouncing that would happen during her running will cause her a great deal of pain. That was why she was holding it : she was easing the pain of her shoulders beforehand. Now that Onii-san thought about it, their weight should be impressive as well and he was somehow very glad to not have to carry such enormous perfections around. For an instant, he wondered just how heavy they were but felt he wasn't really ready to get this information for now. All of sudden, all the memories of their meetings came back to him. All of these times, she never really did anything to stop her mountains from bouncing as soon as she could see him.

- It's completely unfair ! ranted Ai-chan as the train was coming down the station. They should just adjust for girls the distance based on the load we're carrying ! We should be ranked !

Onii-san smiled.

- And where would that put you ?

Ai-chan glanced above her shoulder, annoyed.

- You perfectly know which place I'll be, she plainly replied.

She entered the train with Onii-san following her. He was smiling, amused of the situation. Knowing that she was the busiest girl in the whole high school provided him a great joy. Although, to be fair, he never truely believed that some other girl would come anywhere close to compete with her whopping J-cup bra.

- That would a sight to behold, to see you running like that.

Ai-chan sat on a seat and let her bosom rest on the suitcase she put on her knees. Onii-san tried not to look down at her flesh spreading but did nothing to hide his amused smile. She looked at him, visibly annoyed to see him delighted of her misery. Her huge assets were always there to keep her with the upper hand on their usual discussion but now they turned back on her. And he was enjoying it, surely because once again, they were talking about their incredible sizes.

- Well, since you're already in a good mood, Onii-san, you probably don't need this week's charm, right ?

The sudden look of shock and sadness on his face managed to make her grin.

Ai-chan was breathing really loudly as she ran on the path through the city's park. Her eyes closed in discomfort, the young girl was obviously in pain. The reason for this sad sight on such a pretty girl was not hard to localise. Just under her beautiful face glittering with sweat, her two enormous J-cup mountains were heavily bouncing up and down for several minutes now. The busty girl was not one to be annoyed by the bouncing but running an hour long marathon was almost impossible for her. For each one of her step, her giant bosom would be lifted up, stretching with all their might, almost reaching her chin by their sheer size. This was easy part, the slight moment of relief where for a moment, her chest was almost absent if she was careful enough to keep her chin up to not getting hit by it. But inevitably, as her momentum reached an end and brought her body down, so it did with her breasts. She would usually clench her teeth at that moment as her two bigger-than-her-head mountains would come crashing down on her chest with all their tremendous weight. She could could feel with full force the several kilograms of fat Mother Nature gave her. A soft squeal would usually leave her delicate lips before taking the next step. Each meter was worse than the previous one as her strained shoulders were now begging for her to stop. Her ginormous breasts felt heavier by the minute as the young girl's energy was leaving her. She seemed to be more and more conscious by their unfathomable weight that were threatening to make her stumble at each new step.

This impressive spectacle kept going for dozens of minutes which felt like hours to the "unlucky" girl. From time to time, she would zip up her sport jacket, just to add as little bit of support as she could find. But this effort was ridiculous. How could a sport jacket's zipper could contain such monstruous mounts of flesh ? Her immense chest gave itself a great time to unzip it in barely a few dozens of second for her, abusing with ease this little zipper who thought it could hold it. Desperate, Ai-chan also tried to hold her titanic breasts with her arms in all sort of positions but their weight were way too great for her to be able to hold them for this long. Besides, their sizes alone made it impossible to hold as her flesh kept bouncing around, slipping from her desperate fingers.

Ai-chan had tried several time to speak to her PE teacher about her sizeable "disadvantage" but to no avail as she wasn't really affected by any handicap or disease. She just had to somehow deal with the karma Mother Nature had put on her in exchange of her incredible figure. And what a figure it was ! Boys who were overtaking her were left speechless and gaping at the sight of Ai-chan's huge womanly attributes literraly bursting out of her jacket. The young girl always had an incredible reputation at school but it felt that boys couldn't really understand just how massively huge were here breasts. Even the boys from her classroom were stunned by this new point of view. At this point, Ai-chan just had not enough energy left to scold them. She was just concentrated on carrying her load, her eyes closed in a painful expression. Hence, the boys gave themselves a great time and followed with attention the great magnitude of their beloved girl's imposing chest's bounce.

Two of these boys were actually reducing their speed to see more of this incredible bouncing when a second girl got in between Ai-chan and them.

- Where do you think you're looking? barked Volleybu-chan to the boys who left promptly.

Ai-chan slightly open her eyes, still out-of-breath. She immediately recognised her friend's bosom bouncing at her eye level. "That's weird" managed to thought Ai-chan. Volleybu-chan's chest was quite big as well and yet, it was just slightly moving, despite their size. Just as the busty girl was analyzing her friend's movement, Ai-chan's enormous chest bounced with all their might on her chest making its owner squeal of pain.

"I can't..." she thought, "I can't...continue...any longer".

Ai-chan clenched her teeth but her chest's enormous weight took a malicious pleasure to remind her how incredibly hefty it was. The busty teenager slowly stopped, breathing loudly and sweating buckets. She slouched over putting her hands on her knee, trying to catch her breath. Her strained shoulders, although now relieved of the bouncing of her chest, kept screaming in pain because of the weight of her mountains that were now dangling down. Ai-chan proceed lift her whopping J-cup mounts with her right forearm, letting her shoulders rest a bit.

- Wh-Why ? This...isn't fair... H...how ? she panted menacingly.

- It's because of all the training for volley-ball, Volleybu-Chan replied cheerfully, while running on the spot.

Ai-chan swallowed with difficulty, panting heavily as sweat were sliding down her cheeks and neck. For sure, she wasn't an athletic girl by any means but so were the other girls in their classroom. She looked up to see her friend who was still running on the spot while her large breasts barely jiggling. Ai-chan sighed out of despair.

- That's... not... what… I'm asking..., she continued panting with a gloomy expression.

Ai-chan approached her friend meancingly and reached suddenly to her breasts from behind. They felt so small to her hands but they still manage to greatly full them. She then started to squeeze them just like her friend was always doing it to her. Volleybu-chan squealed of surprise while Ai-chan shouted almost at her angrily :

- How come yours don't move as much even though they're this big ! This isn't fair !

- HYAAAA ! Wh-What's happened to you all of sudden !

Some boys who were still running glanced quickly at them with a red face.

- Oh !? Could it be...

Volleybu-chan put her hands on top of Ai-chan's one, accompanying her in the fondling of her large chest.

- ... you're finally interested in my tone body !? I got it ! she said with an overlyjoyed smile. Let's hurry up and finish this boring marathon and head to our finish line of love and…

Ai-chan sighed of annoyement but couldn't catch her breath well enough to reply to her friend. She stopped to fondle her and tried to let go but Volleybu-chan's hands imprisoned hers and it was her now doing the groping. She carefully moved Ai-chan's indexes with her own to land on her nipples and she kept on malaxing her large breasts with Ai-chan's hands in its own. It was clear that this groping had to be the most beautiful moment in Volleybu-chan's whole year if not life.

- We could go to a love hotel ! she continued overjoyed with bliss. Specifically, one along a highway with neon flashlights and we cou...

For sole answer, Ai-chan squeezed Volleybu-chan's breasts with much more force crushing them violently with her nails, making her moan in pain.

- Ow ! Ow ! Ow ! Ow ! squealed the tall girl

- I'm asking a serious question, said Ai-chan with her teeth clenched before letting her friend's breasts go.

- OK, sorry...

Volleybu-chan turned around and faced her. Taking a serious expression, she cleared her throat.

- It's because of your form : you move up and down too much. The objective is to move forward. So basically, you just need to move smoother like... I dunno... a snake ? she said while wiggling her arm like the animal.

She glanced back to the busiest girl in school :

- Do you get what I am saying ? she said with a smile, happy to help her friend's considerable problem.

- No. plainly replied Ai-chan.

Volleybu-chan scratched the back of her head :

- Well, mine aren't ridiculously huge like yours so...

- Huh, did you say "ridiculously huge" ?

- You're almost 5 cups bigger than me !

- I noticed.

- And I told you to wear a sport bra today.

- I am ! angrilyvretorted Ai-chan.

The young girl cupped her mountains of flesh from beneath and lifted them up. Their enormous masses overflowed greatly in between her fingers as her small hands lifted them. She shook her hands to make her assets heavily jiggle to emphasize the problem to her friend, who was left speechless at the sight. Never in her life she would have thought that Ai-chan would show how huge she was like that.

- I am wearing two of them right now but they're barely holding anything !

Closing her gaping mouth, Volleybu-chan tried to process what she was saying :

- What ? Really ?

Ai-chan lifted her enormous assets higher, pointing them forward her friend, to show her.

- Yes !

Dubious, Volleybu-chan put her hands on both of Ai-chan's breasts who put her fists on her hips, letting her friend see by herself by giving her a free access to her chest for once. Volleybu-chan started to squeeze her friend's J-cup bosom and already she could feel the flesh running in between her fingers, overflowing in every direction. Her hands were too small as well to apprehend the unbelievable volume of her friend's bosom, gently heaving up and down with breathing. The feeling was also incredible. Freed from their usual tight bra in which their owner was usually cruelly placing them, they were now free to occupy as much place they wanted. But besides their gigantic size, two things she did not know were incredible.

The first one was their shape. Despite being almost bigger than her head, both of them kept a perfect round and perky shape, adding to their glory. The two J-cup sized mountains were incredibly firm despite their tremendous volume, proudly sticking out of her chest, with absolutely no trace of sagging. The second one was the softness. Volleybu-Chan had a very nice pair of breasts herself that she enjoyed a lot to play with. But the softness of Ai-chan's bosom was unmatched. It was literally a different category. Never she touched such softness before. The tender flesh of these mountains was letting itself being gently squeezed by her fingers, showing their unique supple structure. Volleybu-chan always knew that Ai-chan's breasts were huge as it was their most striking feat but she would never have thought they would be this perfect. For a second, she couldn't stop her from being a bit jealous. Size, weight, softness, firmness, roundness, beauty, shape... Ai-chan had everything. If only...if only she could see her naked or touch them without anything... No, she was not ready yet to understand how even more perfect she would be.

All these new informations were made possible by the fact that her friend was wearing a sport bra. Well, actually two as Volleybu-chan could definitely feel the two different fold of her sport bras' cups. She swallowed hardly. This girl not only managed to find two sport bra in Japan of her size which was already an incredible feat on its own. But even they weren't enough to hold these two colossal mountains in place.

- Wow... softly whispered Volleybu-chan as a sole answer, unable to stop squeezing them.

She had left all her teasing and joy behind only to express her astonishment and envy. As her hands left the front of Ai-chan's massive bosom and went to its sides, Volleybu-chan directly understood the problem. She was overflowing. And by quite a lot. The athletic girl could easily feel all the flesh bulging from her sides, unable to fit in their designated cups.

- Your bras are too small, replied Volleybu-chan, still dazzled by this new sensation of groping.

- They only had I-cup bras in the store ! justified Ai-chan, complaining a bit. Besides, I thought that you told me the tighter it was, the better !

But Volleybu-chan was not even listening to her. She was just trying to understand how a 16 year-old girl was able to overflow this much two I-cup sport bras. Sure, she knew Ai-chan was a J-cup but she had to be such a big one to have this result. She gently poked her friend's mountains on the side, trying to get them to fit inside the cups. But it was to no avail as Ai-chan had exceedingly already filled them to the rim with her delicious flesh. Volleybu-chan understood it now. Ai-chan couldn't run not because of her posture, not because of her bras... Her breasts were simply way too massive.

Volleybu-chan stopped her futile endeavour and got back to the front were she took again two good handful of her flesh, mesmerized by the new feeling she was experiencing. Meanwhile, more and more boys who were passing by were had began slowing down a bit to enjoy the sight.

- Uh... wh-what are you doing ? asked Ai-chan after a few tens of seconds.

- I'm double-checking. I must verify these claims, replied Volleybu-chan, her eyes lost in her friend's bosom.

- Verify what ? screamed Ai-chan.

The two young girls struggled against each other. Ai-chan was pushed her friend away with all the force of her weak arms while Volleybu-chan struggled to keep her hands on her friend's breasts. Again, a few boys passing by greatly appreciated what they were seeing.

- How long are you gonna touch them ! Stop it already ! grumbled Ai-chan. Let me go !

She tried to run away but her friend couldn't let go of her, running behind her while still fondling her massive breasts. After a few steps, Ai-chan stopped and stayed motionless. Volleybu-chan got closer, her hands still on her friend's breasts.

- What happened? Do you like that thing I do ? she hopefully asked.

- This might be... easier ! replied Ai-chan to her friend's face with so much joy in her voice.

It felt like she was almost being tear-eyed at the idea of not having to cope with their weights anymore.

- I'm counting on your support ! said Ai-chan.

Volleybu-chan's eyes sparkled with tears of joy with the idea of holding Ai-chan's breasts for the rest of the marathon. But she made a quick calculation. They were still so far away from the finishing line, probably more than an hour at their pace. And already, Ai-chan felt so incredibly heavy that even thinking holding them just a few minutes made her arms shake in fear. But before she could tell anything, Ai-chan started running, visibly delighted to have given away her impressive burden to someone else.

- I told you I can't... said Onii-san to a co-worker.

He sighed, a bit annoyed. Once again, his co-worker at the office didn't do his job on time and he was asking him to do it instead.

- Is there really no way ? sadly replied his co-worker, visibly embarrassed.

Onii-san sighed again, showing his disapproval as his phone beeped. He opened it while his co-worker left him some space, worried. It was Ai-chan. It's been quite a long time since they had exchange number but he felt his hear beat faster as he saw she had sent her a picture, waiting to be downloaded. Usually, they would send themselves messages and nothing else. He pressed the download button and waited impatiently for it to be done. His short patience was greatly rewarded as he discovered the picture.

Of course, it was her. She was in front of the finishing line that she probably had just crossed moments before. She was wearing a sport jacket that was widely opened to reveal a white shirt underneath. With a large and satisfied smile and her eyes closed in glee, she was presenting a V with her fingers just like every Japanese girls do on pictures to the person who took the picture. The difference with them was of course around her chest area as she her arms were squeezing her breasts together, revealing her quite enormous masses. Her skin was glittering with sweat and the high-resolution even allowed Onii-san to notice that a drop of her sweat had recently disappeared inside her white shirt. She was simply beautiful. The picture was accompanied with the text "I made it for the first time !"

Onii-san smiled. "So in the end, she made it through" he thought. He was actually quite impressed by how this young girl managed to run with such tremendously huge masses in front of her. He replied to her "Congratulations ! You both really worked hard, huh ?". Ai-chan was prompt to reply "Both ?". Onii-san chuckled before replying "You and your Cooper's ligaments".

On the finishing line of the school, Ai-chan's phone rang and she read the messages while people kept cheering the late runners. Intrigued, she looked at the definition online of a "Cooper's ligament" and saw that it was a indeed a ligament to support and maintain the shape of the breast. Ai-chan turned to look at her friend's who were sitting on the ground around Volleybu-chan. Two of them were putting ice on the swollen forearm of their tearful friend. Ai-chan heard a girl ask Volleybu-chan "Were they really that heavy ?" to which the girl nodded in silence. She had kept her promise and managed to hold Ai-chan's massive bosom during the whole run. She chuckled : she had been a wonderful Cooper's ligament.

Onii-san walked the corridor, his eyes still on the picture she had send her, analyzing the incredible shapes of her beloved angel. As he opened the door to its office, Ai-chan replied with a simple teasing emoji winking and drawing its tongue out. Onii-san sighed with a smile. As he sat down, he dropped Ai-chan's Monday morning charm in the cup. The round button clattered as it joined its defeated comrades, vanquished by Ai-chan's gigantic assets. It was a wonderful Monday.