Kaban no Yuusha no Isekai Nonbiri Tabi ~Jitsuwa "Kaban" wa nani demo Kyuushuu Dekirushi, Nihon kara nandemo Toriyose ga Dekiru Cheat bukideshita~カバンの勇者の異世界のんびり旅～実は「カバン」は何でも吸収できるし、日本から何でも取り寄せができるチート武器でした～; The Relaxed Journey of the Bag Hero in Another World

A high school boy named Keisuke Sakudaira is suddenly summoned to another world just before he enters high school, where he's told he must defeat the Demon King as a hero. However, the sacred weapon (Holy Armament) bestowed upon him is nothing more than his ordinary school bag...!? Soon after, Keisuke is labeled as a defective hero and is abandoned by the queen, his summoner, in the most dangerous dungeon filled with powerful monsters. It seems he is doomed to die... But then, the "useless weapon" the school bag is revealed to have amazing cheat abilities that will change everything! Thus begins the unbelievable journey of a hero traveling through another world armed with nothing but a single bag!