The Sidekick Never Gets the Girl, Let Alone the Protag's Sister!

Then: Kunugi Kou waged bloody warfare as a hero in another world. Now: He's a perfectly average high—schooler with a perfectly exceptional best friend: Ayase Kaito. Kaito's charming personality and looks that could kill have earned himself the harem of quirky beauties that every protagonist deserves-and Kou is dead-set on supporting him from the...