The all-girls Kikyo Private Academy and Chidori Public High School are polar opposites. With its prestigious history, Kikyo is attended by noble young ladies from distinguished families, while Chidori is infamously full of simple-minded delinquents. It is no surprise that their students clash with their differences. Having a tall stature and fierce appearance, Chidori student Rintarou Tsumugi is often avoided by others despite his gentle heart. One day, while helping out at his family's patisserie, he meets a customer who, after a brief moment, runs away from him. The next day, the customer returns to apologize to Rintarou, introducing herself as the cheerful Kaoruko Waguri. After spending time with Kaoruko, Rintarou appreciates that she does not judge him based on his appearance and looks forward to when they will meet again. However, when Rintarou discovers Kaoruko attends Kikyo, their relationship will challenge the social expectations and dynamics around them.

The film follows Ryota Miyagi, the point guard of Shohoku High School's basketball team. He had a brother, Sota, who was three years older than him and inspired his love for basketball. Ryota and his teammates Hanamichi Sakuragi, Takenori Akagi, Hisashi Mitsui, and Kaede Rukawa challenge the inter-high basketball champions, Sannoh Kogyo High School.

The OVA episode revisits the primary matches from the spring tournament and features interviews with players.

The urban legend of the 4:44 ritual consists of using a radio player to produce frequencies in front of the Akeyuki Sacred Tree at exactly 4:44, transporting people to a different dimension. When Asuka Tsuchimiya and her friends—Nana Nanase, Mia Silverstone, Yuu Tounaka, and Chloe Morisu—decide to perform this ritual as an activity of the Crystal Radio Research Club, they are shocked when the ritual works. The five travel to a parallel world, known as a fragment, where they meet an unsettlingly familiar girl—Asuka's parallel-world self. This Asuka is dubbed as Seriouska due to her serious attitude and capability to fight. Seriouska tells them about the great danger that faces all the parallel worlds, the Twilight. As it strips the parallel worlds of all of its possibilities, Seriouska seeks the death of the man behind the Twilight, the Twilight King, to stop his onslaught over the multiverse. Akanesasu Shoujo follows the five girls as they learn to accept their true selves, all the while searching for the Twilight King. However, the solution to the invasive Twilight might be closer than they think.