15-sai, Kyou kara Dousei Hajimemasu.

On his way home from drinking his sorrows away after being rejected by his crush, the 26 year old salaryman, Yoshida, finds a high school girl named Sayu sitting on the side of the road. Yoshida is completely drunk out of his mind and ends up letting Sayu stay at his place overnight. Not having the heart to put Sayu out on the streets since she ran away from home, Yoshida allows her to stay at his place... And so began the awkward, irritable, and slightly heartwarming relationship between a runaway high school girl and a salaryman living together.

It's July 1, 2020. Mizuha, a high school second-year, is having the worst seventeenth birthday ever. She's missing her chance to get close to the older student she admires, and her parents didn't even remember that it's her birthday. Worst of all, there's a new and unknown infectious disease making the rounds, so all her club tournaments and school trips have been canceled. She's convinced that she'll never have the dazzling youth that she's always dreamed of... but then her childhood friend, Mizuki, suddenly declares himself a candidate to be her boyfriend. This is a school youth story about four childhood friends who grew up like family, one being the heroine, Nishino Mizuha, and the four boys she grew up with whom she sees as family.

The story revolves around Tsubasa Sonokawa, a 15-year old high school girl who fell in love with her upperclassman when he saved her after she fainted at the train station from anemia. She thought it was a meeting of fate, and visited him at his class every day. However, he told her that her feelings were "heavy," and he dumped her. She once again meets a boy after taking over her friend Yuri's job as boy's basketball team manager. She learns that she might have more of a connection with this boy named Aki than she first thought...

Seven years after making a childhood promise to always be friends, Hayato is reunited with his formerly tomboyish pal Haruki at a city high school–only now, Haruki has transformed into the girl every guy dreams about! While Haruki’s looks may have changed, with Hayato, she’s still the same pal he remembers. Despite years apart, their promise and feelings remain and deepen into something stronger.