LOVELESS 2 (IDス ZERO-SUMス)

[DeepL Translation - needs review] Aoyagi Rikka, a sixth grader, has lost the only person who understands her when her older brother Kiyoaki was killed two years ago. Then, she is visited by Wagatsuma Kusatoh, a "fighter" who used to fight with Kiyoaki as his master (Sacrifice). Rikka learns that Kiyoaki was killed by an organization called "Natsu no Tsuki," and together with Kusatoh, they challenge the battle and get to the bottom of her brother's death.

(Translator: DeepL)