fukushuu_wo_koinegau_saikyou_yuusha_wa_yami_no_chikara_de_senmetsu_musou_suru
Fukushuu wo Koinegau Saikyou Yuusha wa, Yami no Chikara de Senmetsu Musou Suru
Unofficial English title: The Dark Massacre of the Vengeful Hero
Literal English title as seen on cover pages: The strongest brave who craves for revenge, extinguish with the power of darkness
Light novel authored by Ononata Manimani and character design by Araya (Hachino Araya); manga illustrated by Sakamoto Akira.