The Twins' CircumstancesFutago-tachi no Sho Jijou; Futagotachi no Shyojijyou; The Personal Circumstances of the Twins.; 双子たちの諸事情; 雙胞胎之間的那些事

Kouki and Nao are siblings that harbor feelings for each other that they're not allowed to express since they're 'twins'. "I locked away the key gently in my heart but mom reveals a secret about Kouki!" "The person I like is my twin!" Pure 120% romcom, start!