Glass no Futatsuba (Hana Marubunko BLACK)

[Machine Translation] Tomoki Ihara is an ordinary salaryman. He lives a peaceful life with his twin high school students, Kanasuke and Takumi, who are his late wife's stepchildren. One day, one of his senior employees recommends that he remarry and introduces him to his girlfriend. When the twins find out about this, they throw away their conventional good-natured attitude and attack Tomoki! The twins have decided to have their first sexual encounter with their father, and the nightly sexual feast with the twins unfolds. Tomoki is completely worn out, but Makimura, his junior at work, shows some signs of caring for him...?

井原智記はごく普通のサラリーマン。実年齢より若く見えるが、亡き妻の連れ子で双子の高校生、奏佑・巧佑と3人で穏やかに暮らしていた。ある日、先輩社員から再婚を勧められ、交際相手も紹介される。先輩の手前、仕方なく相手の女性とやり取りを始めるが、それを知った双子たちは今までの聞きわけのよさをかなぐり捨てて、智記に襲いかかってきた!!「俺たち、決めてたんだ」「初めては父さんにしようって」双子相手に夜ごと繰り広げられる性の饗宴。すっかりやつれ果てた智記だが、会社の後輩である牧村はいたわるような素振りを見せてきて...!?