Isekai-gaeri no Kensei wa, Jibun no Jitsuryoku ni Kigatsukanai: SSS Rank no Kakushi Quest wo Ukete Kaettekitara Level 1 no F-kyuu Tansakusha ni Natta kedo, Isekai de Kitaeageta Kenjutsu ga Tsuyosugite Oujo ya S-kyuu Eiyuutachi ga Ore wo Hanattekuremasen

"The Weakest Explorer," Akizuki Yuuta had accepted a hidden quest and was sent to another world. His daily life changed to a very hard adventure, continuously fighting against an endless amount of powerful monsters. And so, when he returned from another world, although he had gone back to being level 1, he had retained his otherwordly swordsmanship skills...! The weakest explorer has become the strongest sword saint! The unyielding warrior returns from another world! (Source: Kodansha, translated)