The Flamechaser's Therapist

Y/N Was a citizen in Sundown Valley, who lived together with Kalpas, Sakura and Aponia. The honkai razed the Sundown Valley to the ground. Almost everyone died. But Y/N sacrificed himself to make Aponia, Sakura and Kalpas run. But he survived, luckily, he didn't have too severe wounds when he woke up. That's strange, he had gotten stabbed in the stomach and had a wide hole in his stomach.
Y/N didn't think much of it and later on met Kevin, Su and MEI in highschool.
Unfortunately, Honkai struck there too. Y/N was seperated by everyone he knew. All due to the honkai. Now after a few years after their seperation, Y/N gets a job offer. As the flamechaser's... therapist?