Izuku sat on his favorite couch in the world, the soft, plush, incredibly comfortable couch of the Bakugou's living room.
He was tempted to just lean back and take a nap on the soft fabric with cushions the perfect size and shape for him, but he stayed sat up with his legs crossed underneath him. He could feel the small weight of the recording device sitting on his leg, on and taking in every sound, including the TV playing in front of him. But he wasn't listening to that, he was more closely listening to Kacchan beside him, narrating the fight that was happening on screen.
"Endeavor swings a right hook, quirk activated," Kacchan said in a deadpan. He did this a lot and it showed. "The villain dodges to the left, coming in with a swipe of the stinger and-" he hissed. "The fire blow flies back and inflames the entrance of a building people were trying to get out of."
Izuku sighs in frustration and reaches to stop the recording. "Switch the channel. What time is it?"
Izuku here's buttons click and the sound of the TV changes. "Bout six-thirty."
Izuku slips the deceive in his pocket. "I probably need to get going then, mom doesn't want me home late and I still wanna stop by the library."
Kacchan just grunts in acknowledgment and starts to move towards the staircase. "Alright, see ya tomorrow then, nerd."
Izuku just smiles. "Bye, Kacchan!"
He felt a new set of feet move from the kitchen towards the living room, and heard Auntie huff. "That brat's gonna end up all alone with that attitude."
Izuku smiled. "It's fine, Auntie. I know he doesn't mean anything by it."
She huffed. "Maybe you do, but other people won't." She spun back to face him.
Just as he was turning around towards the front door to out his shoes on, some heavy container of sorts was dropped into his arms.
"Heard you two were struggling with money a bit, and Inko had to take on more shifts. Figured you could use something to eat when she's not home to cook. You still like Katsudon, don't you?"
Izuku nodded with a grin. "Yeah, I love it. Thank you so much, Auntie! You really didn't have to."
She wacked him on the shoulder playfully. "Ah, don't worry about it, kiddo. It was really no problem at all. Tell your mom I said hi, and to call me. We haven't been talking enough recently."
Izuku nodded. "I will. Thanks again, Auntie. Goodbye!"
Once he had his shoes on and his backpack on his back with the food inside, he headed out the door and started down the sidewalk. He went in the direction of his apartment to start. He didn't know the route from the Bakugou's house to the library well enough yet, but he did know it from his house.
About 30 or so minutes later of walking, he arrived at Musutafu's main library. Just his footsteps vibrations couldn't reach the whole building, but he knew it was pretty big. He'd been here a few times, because they had a section of books written in braille that he liked being able to use. Sometimes braille written books were easier then the audio based research.
When he walked inside to the main entrance, he immediately heard a voice and felt a chair move.
"Ah! Midoriya, hello," came the cheery voice of Mrs. Orochi, the young librarian who ran the front desk. "It's good to see you back, been a little bit since you came by."
Izuku smiled in her direction. "Hi Mrs. Orochi! Yeah, I've been trying online research a lot more recently, trying to get used to some of the new audio tech my friend got me. So I haven't had a need to come by for a while."
"Well it's good to see you here again. I'm assuming you still know your way to the braille section. Would you like some help finding what you're looking for?"
He nodded. "Yes please, thank you."
He felt footsteps approaching. "Of course! What is it you're looking for?"
He started to follow her towards the back of the building. "I wanna do some research on echolocation mainly, how animals use it and stuff. I've been curious about whether or not there's any way I could incorporate it into my quirk."
He'd heard of it before and done a bit of research, but had brushed it off pretty quick because, while it was similar to his quirk, it used sound, not vibrations. But recently, Hitoshi had found something on the internet about how sound waves were basically vibrations through the air, and that gave him an idea.
If he could figure out how to tap into the vibrations caused by sound waves in the air, he could use it to see things better at the beach, which yes, he was still struggling with despite it having been several weeks since they started. He could also maybe use it to see things coming at him through the air, which was one of his worst weaknesses.
"Oh!" The woman clapped her hands excitedly. "That's good thinking, I didn't even think of that when you came here to look at stuff about animals who used vibrations. But echolocation is quite similar to your quirk, isn't it?"
Izuku nodded. "It'll help a lot if I can at least do something similar."
"Of course, well," they stepped into the section he'd become familiar with, "I'll help you look for some books on the subject. We should have at least some over here."
"Oh no, you don't have to do that."
"Nonsense," she already started walking towards a corner. "The librarie's pretty empty right now, and Lilie's up by the front desk too, so I have time."
Izuku let out a sigh but smiled. "Alright, thank you."
"Of course!"
He started to run his finger along the section labels in braille, trying to find where the books he's looking for would be.
He liked Mrs. Orochi a lot, she was always kind and helped out in any way she could, but she never felt like she didn't trust him in his own or anything like that. She actually had an interest in braille and knew how to read it, so she helped a lot when he was learning. Sometimes she'd come here just to get away from the rest of the world for a bit, and she was always understanding. She felt like a good friend of his.
It took about half an hour, but finally Izuku ended up at a table with about five books on echolocation and vibrations in braille.
He also brought and listened to his older recorded study of echolocation.
Echolocation was basically an animal using sound waves bouncing off of nearby objects and back to their ears to read their surroundings, much like what he did with vibrations, except sound can go through the air.
Sound waves were all about vibrations. Whatever creates the noise vibrates, causing the air molecules around it to vibrate, which vibrates other air molecules, creating a wave the ripples through the air before eventually reaching your eardrum, which also vibrates.
He needed to figure out how he could feel those vibrations. The only issue was that the vibrations caused by sounds were extremely weak compared to what he normally feels.
Music has to be pretty loud and deep for a normal person to hear it. While he's much more sensitive to the vibrations, he's never noticed vibrations from normal sound, so he probably can't feel it that easily. And he's never been able to feel air molecules vibrate.
He and no idea where to start to figuring out how to do this, or if it was even possible. But this was the closest he'd ever gotten to being able to cover his weakness for the air.
If he can learn to use vibrations from sound like echolocation with bats, or how some whales do in the water, it would make heroics a whole lot easier for him. So he had to try.
He was going to need help, though.