Nido Tensei shita Shonen wa S-Rank Bokensha to shite Heion ni Sugosu 3 (Gangan Comics UP!)

[Machine Translation] The strongest boy who reincarnated twice kills a legendary demon in a second! A demon and a gate...let's destroy them all together! Lex, a boy who has been reincarnated twice, easily defeats a legendary demon who appears while he is training his prefects. Although he wanted to live a "simple" life, Lex is promoted to rank B at once, and finally leaves his familiar town...! The heroine finally makes an appearance! The unaware warriors move on to the next stage! The third volume of this exciting adventure fantasy!

二度転生した最強少年、伝説の魔人を秒殺！？「魔人とゲート…まとめて壊しちゃうか！」二度転生した少年・レクスは、舎弟たちへの修行のさなかに現れた伝説の魔人をあっさり倒してしまう。「地味」に生きたいはずなのに、Bランクに一気に昇格したレクスは、慣れ親しんだ街をついに出る…！？ヒロインもついに登場！無自覚無双は次のステージへ！？痛快冒険ファンタジー、第3巻！