Gimai Shinkon: Kyorikan Okashii Giri no Imouto ga Guigui Kurunda ga!?

Kazuma Hanamiya is an earnest, dedicated office worker who is well-liked by both his female coworkers and junior colleagues alike. Truth be told, he recently tied the knot—though his bride is none other than his stepsister Nagisa Hanamiya...?! It's the start of a super-sweet newlywed life, featuring an overly kind older brother and his intensely devoted younger sister (now wife)! (Source: Takeshobo, translated)