Kouun no Shokichi ga Ijou ni Takakatta Koukousei ga, Kanzume Gacha de Te ni Ireta Skill wo Tsukatte Gendai Dungeon de Saikyou ni Naru Monogatari

Ten years ago, mysterious, laid-back characters called Danpons arrived from another world and created dungeons that have become a part of everyday life in Japan.

High school student Taira Ichino is invited by friends to explore the dungeon at Osaka Umeda Station. However, the place is teeming with people, making it impossible to defeat monsters properly. All he acquires are minimal experience points and a mysterious canned item called the "D-Can," whose contents and method of opening remain unknown.

Back home, as Taira yearns for a personal dungeon, the D-Can suddenly opens. Inside, he discovers a candy that allows him to learn skills.

This is the story of an ordinary high school student who, through sheer luck alone, sets his sights on a goal and relentlessly strives to become the strongest explorer.

(Source: Bushiroad Works, translated)