世界 (Series) favorite_border

[DeepL Translation - needs review] Volume 1 Introduction: Siblings Hitsuuchi Sotoki and Hitsuuchi Yatsuki, who are currently crossing a forbidden line, and their friends, Geki Tsuki Hakohiko and Kotohara Ririsu. Their friends, Hakohiko Geitsuki and Ririsu Kotohara. Their world is decisively cracked by a locked-room murder in the school. ...... Sankoku sets out to solve the case with a recluse in the infirmary, Kuroko Neko of Hospital Slope...

(Translator: DeepL)