Ennoshita no Chikara Mocha: Maou Toubatsu Shitara Wakagaetta node, Gakuen de Kage kara Support Shimasu

Sakuya just wanted to be a "behind-the-scenes" support hero, but after defeating the Demon King almost single-handedly, he was rejuvenated. While searching for his next goal in life, he came to the academy that trained new adventurers. There he met Fuyuna, the strongest swordsman in the school. Seeing Fuyuna burning to compete with the other academies, Sakuya supported her from the shadows as a fringe member of the academy....... He was supposed to be strong, but he didn't want to appear too strong to stand out! (Source: Dragon Novels, translated)