I don't own Dragon Ball and Kimetsu No Yaiba Dragon ball is owned by Akira Toriyama and Kimetsu No Yaiba is owned by Koyoharu Gotouge.

Author note:

I have decided to use this version of Chapter 3 that Tanjiro is taught the Kaio-ken by Goku which changes future battles.

Last time Goku easily learned concentrated breathing along with the ten water breathing forms in a few days and successfully cut the boulder in one go and wanted to wait for Tanjiro along with helping train.

Chapter 3

Goku is thinking about trying to teach Tanjiro the kaio-ken because he thinks it will be useful in future battles, Tanjiro part trained for 6 months by himself while Goku was trying to improve to kaio-ken times three which he could hold for a short while and can he hold kaio-ken times 2 for a while like five to seven minutes currently.

A mysterious figure engaged Tanjiro with a wood sword and told him to try and act like a man Goku got confused since he can't sense the guy's ki energy so Goku figured out it's spirit of a dead person and kept the truth away from Tanjiro.

Then a young girl appeared confusing Tanjiro but not Goku since he knows it's another spirit. Goku has seen other spirits like this once before while he was trapped in a different dimension but back then he was still a grown man and could transform.

Meanwhile in the Dragon Ball Universe a city has become under attack by two high powered beings with negative energy and the one to engage them is Vegeta alone and Vegeta is shocked to see that Towa and Mira are still alive.

Vegeta ends up asking them what did you do with Kakarot? After turning straight to Super Saiyan Blue and Towa answer by saying we took away all of this God ki and make sure he can't go Super Saiyan, Super Saiyan 2 and Super Saiyan 3, we also made sure that he cannot fly and use instant transmission.

Vegeta says you bastards I wanted to defeat that clown myself. Oh and I want to kill both of you revenging all the other versions of me you killed from other timelines. Tora asked how do you know about that and Vegeta says I met a version of me that has God ki and a form called Super Saiyan 4 ( of course talking about Xeno Vegeta) and says bring Kakarot back now or else.

Tora and Mira just left the area and are thinking about doing what they did to Goku to Vegeta but they passed on that because they think that Goku and Vegeta would just use fusion and the fusion would use kaio-ken to try and stand a chance.

Back to the Kimetsu No Yaiba Universe with Goku, Tanjiro, Sabito and Makako.

So far Tanjiro has trained for two years so Tanjiro and Goku now know that boy is called Sabito and the girl is called Makako and Tanjiro has finally cut the boulder in half completing his training. A few months before Tanjiro cut the boulder Sabito and Makako agreed with allowing Goku to teach Tanjiro the kaio-ken technique but Tanjiro can only use kaio-ken times 1.5 for like one to two and a half minutes. Urokodaki comes up and says I never planned on sending you to the final selection because I don't want to see another child die and calls Tanjiro a wonderful kid.

Nezuko has been a sleep for over 2 years and is still sleeping so Urokodaki says that this may just be a hunch that she recovers her energy through sleep instead of consuming human flesh and blood. Tanjiro and Goku both end up going to the final selection and they say to Urokodaki say hello to Sabito and Makako for us and Urokodaki in his head goes Tanjiro and Goku how do you know the names of those dead children.

Tanjiro and Goku arrive at the final selection and see alot of other people. One girl and one boy appear and say greetings everyone thank you for gathering tonight for the final selection. Mount Fujikasane holds demons that demon-slayer swordsmen have taken alive and trapped here. Demons hate Wisteria flowers which bloom here even out of season. They cover the Mountain from its foot to halfway up the slope. However from that point onwards the Wisteria does not bloom so demons are roaming free and you have to survive 7 days in there and if you do then you have passed the final selection now go.

For a while Goku stays with Tanjiro and Tanjiro smells two demons and Goku sensed then a long time ago Tanjiro easily kills both demons and picks up a horrible smell along with Goku sensing a big amount of negative ki and to there shock they both see a giant demon with a lot of huge hands chasing someone and also saw the demon eat another person whole. Tanjiro uses water breathing second form water wheel to save the boy and Goku shoots a ki blast in the demon's face. The demon see both Tanjiro and Goku with fox masks and says oh another two foxes has come.

Sabito and Makako are wondering if Tanjiro and Goku can really do it. Makako asks Sabito if Goku and Tanjiro could do it and he says I don't know but no amount of effort is too much and you know that right? Anyway they can use that kaio-ken technique to multiply their strength and speed by 1.5 or 2 times.

The demon goes tell me fox boys right now what Meiji Emperor sits upon the Throne? Goku doesn't know how to answer but Tanjiro answers the Imperial family is Taisho! The demon goes I have been here so long that Dynasties have risen and fallen again and again all while I've been trapped here!

Damn Urokodaki, damn Urokodaki damn him! Damn Urokodaki. Tanjiro you know Urokodaki? Oh I know him! Urokodaki was the one who captured me! I will never forget it! It's been 47 torturous years! Back then he was still a demon slayer in the Edo period the Keio era!

Tanjiro though demon hunter Edo period?! The boy Tanjiro saved says no way you're lying no demon has lived that long, lies. They only put demons up here that have eaten two or three people and get killed during the selection also demons eat each other too! Goku says I can sense that demon has eat like 50 people I think. The hand demon says how do you know how many I have eaten? Goku response is I can sense energy and aura.

Flashback to Urokodaki sharing information with Tanjiro and Goku remember a demon's strength comes from the number of people it has consumed. So if it eats many more people it gets stronger? That's right they grow stronger and some physically change, gaining unnatural powers. Even know Goku has some unnatural powers and he's not a demon. Plus Tanjiro if your nose gets stronger you'll be able to tell how many people a demon has eaten. While I think Goku who can sense life energy and now aura might already be able to tell.

The hand demon goes 12, 13 and both of you've are numbers 14 and 15. Tanjiro asks what are you talking about? That's how many of Urokodaki's students I have eaten! I've decided to kill all of his students. Goku says well your not eating us. Hahaha heeheehee from the demon what makes you think I can't? Me Goku says I will also avenge Sabito and Makako you monster. Tanjiro is shocked hearing Goku say that but Goku they were this us they helped train me, yeah but I already knew that they were spirits because it happened with me before I can't remember that other Universe thou. Tanjiro is getting ready to revenge Sabito and Makako but Goku stops him and says I sense something is wrong.

Dark negative energy surrounds the hand demon making him more powerful and Goku goes that energy I recognise it so this must be Towa and Mira's doing I guess the safest way to deal with the demon is to use the solar flare technique (so sorry for borrowing your move Tien but I need it) Tanjiro cover your eyes, why? Well I don't want you blinded, OK. Solar flare times three Tanjiro you can now open your eyes OK so what happened to the demon? It's dead I killed it with that technique. You could have told me that you can summon sun light from your body, sorry it's one of my friends techniques.

Well then the hand demon is dead Goku did it he avenged you guys and all the other children that were killed will also return just as was promised. Even though they are only spirits now. Return back to be by their beloved Urokodaki Sensie's side back to their home narrow mist mountain. If me and Goku die our spirits will return to where Nezuko and Urokodaki Sensei are.

Well let's continue towards finishing this final selection right let's do this. Tanjiro yes Goku what is it I can only sense another 4 people left. At the end of 7 days early in the morning. They hear welcome back, congratulations being safe and sound is better than anything else. Tanjiro thinks there's only 5 left but Goku said there's a sixth and I don't see a sixth. Goku and Tanjiro look at a boy say will die five times over even if we survived we'll still die in the end.

Another boy goes eh? What do I do? What about the Blade?

The boy and girl says you must first pay the cost of the uniform, then you must get your body measured and have your rank engraved. Tanjiro what do I do? I have no money on me, really I might have enough to get both of ours I hope. One of the boys asked what about the blade? Today, you will each choose a chunk of Tamahagane alloy. Your blade will be completed within 10 to 15 days. 10 to 15 days hmm I can get so training in that time. Ooh I am so hungry I feel like I could starve to death. There are ten ranks in total 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 9th and the 10th, you are now lowest 10th level. Also from now on kasusagarasu will be following you all.

Goku tried not to laugh went the blonde boy got a sparrow instead of a crow. Kasusagarasu is a crow that primarily used for communication. One of the boys went I don't care about some dumb crow! What I want is the blade right now! The blade of the demon hunters! The "blade of colour change"! Goku sees Tanjiro grab hold of the boys arm going let go of her this instant! If you don't I'll break your arm. Huh? Who are you? You can try if you dare! Tanjiro breaths and almost breaks his arm. Are you done? If so please go over there and choose the alloy that will create your blade.

The alloy for the blade that will be used to destroy demons and protect yourself will be chosen personally by each of you. The blonde boys says I'll probably die really quickly. Back at a building a man with a crow says is that so there are six people remaining they seem to be excellent, my swordsmen have increased... I wonder what kind of swordsmen they all are.

Meanwhile back in the Dragon Ball Universe Vegeta informs the Bulma and the Z fighters that Tora and Mira are behind the wormhole that took Goku. Everyone was shocked hearing this and Bulma tries to work on the Machine to get Goku back quicker since Beerus demands it since they need Goku for the up coming tournament of power.

Author notes:

Well looks like the Dragon Ball Universe is in danger if they can't get Goku back in time for the tournament of power. Well two years have gone by in the Kimetsu No Yaiba universe and just a few weeks in the Dragon Ball Universe.

Well chapter 4 is going to take a while since I will part be taking a break. Since I have made 2 different versions of Chapter 3.