Hitsuji no Kawa wo Kita Kemono

Daichi's big sister is getting married, and to a super hot guy named Jun Igawa! When they first meet, Daichi's suspicious; what does this accomplished, rich, attractive guy see in his sister? But Jun seems like such a nice guy, and slowly, Daichi starts to drop his guard… is Jun really everything he seems? Or is he a devil in disguise?