[Demon Slayer Crossover] The Chances of a Happy Ending with My Scumbag Senior Brother

[Complete] I’ll fix any typos when I have time. [Still in a quiet corner of the fandom. Maybe we’ll meet again someday.] Inadama Kaigaku thought his junior was annoying. He cried and whined all day, was timid and useless, short and shabby, and stupid. He was always getting fooled by women, and the color of his hair was disgusting, too. “If only Agatsuma Zenitsu would get lost and stop sticking so close to me.” He thought that all the time. But the next day, he still had to accept his fate and drag the soundly sleeping blond loser out of bed to train. He was always clinging to him, impossible to shake off! So annoying! “I’m gonna die, aaaaaah! Big Bro is a demon! How could anyone possibly do that?! Waaaaah, I can’t do it! I’m not going to get killed by a monster or a demon, I’m going to die from Big Bro’s training instead?! You’ve got to be kidding! If I die, it’s definitely Big Bro’s fault!” “You’re so loud!! If you have the energy to cry, run faster!!” “You’re even louder than me!!!” Tch, what a pain. I have to go drag that loser out of bed for training again today. CP: Thunder Brothers (no fixed roles, but Zenitsu takes the initiative; read with caution if that bothers you) Crossover, mainly Demon Slayer, also Inuyasha, Noragami, and Hozuki's Coolheadedness (not the Demon Slayer world, no Tsugikuni brothers). Please don't call Kaigaku trash in the comments. Please don't call Kaigaku trash in the comments. Please don't call Kaigaku trash in the comments. I know he's trash, thank you. At heart, this is a story of redemption, a fix-it fic, and a sweet happy ending. [Please don't mention this story on forums or under other people's works. Thank you, lots of love~] Content warnings: 1. Kaigaku's personality differs somewhat from the original, but at heart he's still the same Kaigaku. He can be pretty awful. 2. Due to my interpretation of the characters and my writing ability, there may be some OOC moments. I'll do my best to keep them true to their characterizations. 3. There is a lot of personal headcanon and invention, mainly about Kaigaku's past (just... my personal tastes). 4. Kaigaku has a bit of a special advantage for plot reasons. Don't read if that bothers you. 5. This is self-indulgent ship fic, my first time writing, and I'm bad at blurbs. I have no outline. It's a free story written for love, fully drafted and completed. I'll post it slowly, with daily updates. Please don't curse at me, thank you. If you stop reading, please don't tell me either. I'm begging you. That's all for now. I'll add more if I think of anything (my defenses are stronger than my health). Theme: Everything has a crack. That's where the light gets in.