Kyoukai Senjou no Horizon - Volume 1, School Rules

The 7-year-old little crybaby met 11-year-old big brother who ran away from home.
[This man became the protector of redemption in his life]

The 16-year-old little dragon fell in love with a 20-year-old big brother.
[It’s a pity that the big brother didn’t recognize him as the little crybaby]

The 23-year-old single father and 27-year-old chief executive meets again.
[This time the little crybaby and his big brother are finally together]

Fortunately we met through hundreds of millions of people, Thank God, for letting us break through many obstacles and get back together again, falling in love with you and being with you again is the greatest fortune in my life.

- Description from Novelupdates

As Orson read the novel written by the girlfriend who had left him, he gently remarked on how terrible the story was. But then, noticing a foul smell coming from the kitchen, he went to investigate. He realized there was some kind of gas leak. Already furious about being dumped, Orson became even angrier at the state of his kitchen, and in his rage, he hit the light switch with a powerful punch. Naturally, the explosion that followed killed him instantly, and Orson passed into the afterlife.After spending some time in limbo, he found himself reincarnated in an unfamiliar world. However, he quickly realized he had been reborn inside the cliché-filled novel written by his ex-girlfriend. As if that wasn’t enough, he had ended up in the body of Neonidas, a useless duke who was also the fiancé of the story's villainess.____There may be a bit too much swearing and slang in the first chapters, but it gets less afterwards.There will be no yuri, bl or ntr in Neonidas(MC) harem

I don’t need any deep relationships. I have no desire for a girlfriend, and I only require one friend who holds any value to me. Ever since I threw out my youth for the sake of efficiency, there is one person who keeps entering the bedroom of Ooboshi Akiteru. She’s neither my little sister nor my friend. She’s nothing more than a bothersome, annoying Kouhai, as well as my friend’s little sister: Kohinata Iroha.

“Senpai, let’s go on a date~! Did you think I’d say that~?”

Rather than blood, it seems like energy drinks run through her veins. She keeps occupying my bed, and she tries her best to seduce me with whatever method she can play to her favor. She’s a girl who’s constantly annoying and obnoxious around me. Even though I’m busy all day long, she doesn’t care.

And in case you’re wondering why all these envious gazes are directed at me, it’s because Iroha is actually really popular. She’s an honor student at our school with top grades to boot, and she’s known for being kind and proper to anyone she meets.

…Hey now, why are you only so annoying when you’re around me?

Crippled by the loneliness of life and now the sudden death of the only person that treated her as a human. With strong feelings, Megumi scorn's life end abruptly as she wished to re-join her friend Eric, in death... Only.... She wakes up in the same room feeling an eerie change to her surroundings.Behind her stands a Reaper! Revealing her death to be true, she now finds herself separated from Eric in the world of Purgatory. A world of death where demons are born, the reapers sow and the sins of man become alive!