Dungeon de Nariagare! Osananajimi kara no Kirawarete Goblin ni Saekate Nakatta Ore ga, Dungeon Ruler no Shidou wo Uketara Tsuyoku Nareta no de Imouto to Musou shimasu

It has been 30 years since dungeons were established in Japan.\r\nKyoichi has been accepted into the same extremely difficult high school as his childhood fiancée, Tsubaki, but... Rumor has it that he kneels before a goblin, and he becomes the target of class teasing.\r\nHe tries to turn the situation around by exploring a dungeon, but is beaten up by a group of goblins.\r\nThinking of his younger sister, Koyoi, he is ready to die, but...\r\nHe is saved by a dungeon ruler named Kyoji.\r\nThis encounter changes Kyoji's destiny.\r\n\r\nEvery time you fight, you get stronger and stronger!\r\nThe Warriors' Dungeon Adventure with his sister is about to begin!