Based on the one-shot manga .

One summer vacation, Ruka meets two boys, "Umi" and "Sora," whose upbringing contains strange and wonderful secrets. Drawn to their beautiful swimming, almost more like flying, Ruka and the adults who know them are intertwined in a complex mesh... Meanwhile, an unexplained anomaly is occurring all over the world: fish are disappearing. Thus begins a marine adventure of boys and girls to captivate all the senses!

With a stray pitch that completely missed the batter, Eijun Sawamura loses his final middle school baseball game. Frustrated by this defeat, Eijun and his teammates vow to reach the national tournament once they are in high school. But everything changes when a scout unexpectedly invites him to Tokyo's prestigious Seidou High School after seeing the potential in his unusual pitching style. Encouraged by his teammates, Eijun accepts the offer, ready to improve his skills and play at a much more competitive level of baseball. However, now surrounded by a large number of skilled players, Eijun struggles to find his place on the team. He declares that he will one day become the team's ace, but that's only if fellow first year Satoru Furuya doesn't take the title first, with his breakneck fastballs that earn him a coveted spot on the starting roster. With the addition of these talented new players to an already powerful lineup, the Seidou baseball team aims to become the best in Japan, facing off against a number of formidable foes that stand in their way. [Written by MAL Rewrite]

Nijiiro Days follows the colorful lives and romantic relationships of four high school boys—Natsuki Hashiba, a dreamer with delusions of love; Tomoya Matsunaga, a narcissistic playboy who has multiple girlfriends; Keiichi Katakura, a kinky sadist who always carries a whip; and Tsuyoshi Naoe, an otaku who has a cosplaying girlfriend. When his girlfriend unceremoniously dumps him on Christmas Eve, Natsuki breaks down in tears in the middle of the street and is offered tissues by a girl in a Santa Claus suit. He instantly falls in love with this girl, Anna Kobayakawa, who fortunately attends the same school as him. Natsuki's pursuit of Anna should have been simple and uneventful; however, much to his dismay, his nosy friends constantly meddle in his relationship, as they strive to succeed in their own endeavors of love. [Written by MAL Rewrite]