Jitaku Ni Dan John Ga Dekita. (BK Books) [Light Novel]

[Machine Translation] A middle-aged man who loves beef bowls stands up against a state-level conspiracy! Naoto Yamagishi was unemployed due to a scandal at his workplace, but his life was changed forever by a miniature-sized dungeon that appeared in a drawer in his home. Just by defeating monsters so small that he can crush them with his fingers, Yamagishi is able to super-level up to the point where he outperforms the average adventurer. However, for a man who just wants to live peacefully, his great power only brings trouble. Just as he is about to decide not to abuse it, a junior student, who has been turned into a beautiful girl by a suspicious drug, comes to him for help, which eventually leads to a major incident that will affect the whole country.

牛丼大好き中年男が国家レベルの陰謀に立ち向かう!!職場の不祥事のせいで無職となってしまった山岸直人だったが、彼の人生は自宅の引き出しに現れたミニチュアサイズのダンジョンによって一変した。指で潰せるほど小さいモンスターたちを倒すだけで、並みいる冒険者たちを圧倒するほど超レベルアップする山岸。しかし平穏に生きたいだけの彼にとって大きな力は厄介事を呼ぶだけ。悪用しないでおこうと思っていた矢先、怪しい薬で美少女化させられた後輩が助けを求めてきて、それはやがて国にも影響を与える大事件へと繋がっていくのだった。