A Part of Me Who Died on Sunday

A Part of Me Who Died on Sunday is an episodic prequel to the events of Sensei Overnight. Follow the story of Noko Otana, an orphan and twin brother to Niyama Otana. Siblings who now come from different environments, they always find the time to meet up at a park, right in between their respective schools and homes. However, as they both prepare to return to middle school after winter break, an unexpected letter arrives for one of them that is destined to challenge their relationship.

[From Itch.io]