The 6th season of Huyao Xiao Hongniang

Kenshiro is the heir of the legendary martial arts known as Hokuto Shinken, which can kill a man with a single blow, by striking the pressure points in the enemy's body. Hokuto Shinken can be passed only to one successor at a time. When he was chosen as the successor, he parted ways with his brothers, Toki and Raoh. The former decided to use what he knew of the art to cure people... while the latter has chosen to use his supreme strength to install peace in the world by power. Kenshiro is accompanied by Lynn and Bart, and the movie's story begins when an overlord starts kidnapping children to use them as slaves for building his own pyramid... (Source: AniDB)

Last of the Shin Kyuuseishu Densetsu pentalogy. A prequel set between Kenshiro's defeat at the hands of Shin and the beginning of the manga.

One normal school day, Rikka Takanashi notices Makoto Isshiki secretly passing a flash drive to Yuuta Togashi. Curious, Rikka talks to her friends about the case, who agree that Yuuta is hiding something from her. They decide to discover the contents of the flash drive by any means necessary, but to their surprise, it merely contained pictures of an idol that Yuuta adored back in middle school. However, Rikka takes offense, as she claims that this breaks their contract as lovers and demands Yuuta to return the flash drive. Although having seen Yuuta return the flash drive, she still felt uncertain about the situation. This leads to her sneaking into Yuuta's room during the night, only to find out that the flash drive had not been returned! Scanning through its contents, she hurriedly rushes to bed when Yuuta enters her room. To her terror, she finds the flash drive crushed due to her negligence in keeping it in a safe place. Yuuta quickly finds out and demands an apology. However, Rikka too, demands an apology from him, resulting in both of them refusing to be the one to apologize first. Will the two lovebirds be able to resolve their argument? [Written by MAL Rewrite]