Kakkou no Iinazuke (A Couple of Cuckoos) 13 (Monthly Shonen Magazine KC)

[Machine Translation] The big event, the Megurogawa High School Festival has begun! If they lose in the "M-1" after the festival, they may have to move in together! The "Forgiveness and Marriage Relationship" is in full swing! Nagi Unno, a sophomore at a prestigious private high school, was mistakenly adopted by a different family when she was a baby. One day, she runs into Erika Amano, a very young high school girl who is about to meet her daughter-in-law, and half-heartedly asks her to pretend to be her boyfriend. However, they had no way of knowing this at the time. Erika is a child who was mistaken for Nagi, and Nagi is Erika's ex-wife. ...... A romantic comedy of intertwined lives begins with a "mistaken child"! The big event, the Megurogawa High School Cultural Festival has begun! Nagi and Erika go around the school together, which is surprisingly fresh! Tension is building up for the "M-1" festival later in the evening. If they lose, their cohabitation will be dissolved! What is the "bomb" they have prepared for the big stage...! The "marriage relationship" develops rapidly through the festival! What is Soichiro's intention? What is Soichiro's plan, and what is the answer that Nagi came up with!

一大イベント・目黒川学園高校文化祭開幕！！　後夜祭“M－1”で負けたら同居解消の危機！？　“許嫁関係”急展開！！赤ちゃんの頃に取り違えられ、今は名門私立に通う高校 2年の海野凪。ある日、これから許嫁に会いにいくという超お嬢様女子高生・天野エリカと偶然出会い、彼氏のフリをしてくれと半ば強引に頼まれてしまう。だが、その時の二人は知る由もなかった。エリカは凪と取り違えられた子どもで、凪はエリカの許嫁相手だということを……。「取り違え子」から始まる人生交錯ラブコメ開幕！一大イベント・目黒川学園高校文化祭開幕！！　凪とエリカは校内を二人で回るのが意外に新鮮！　後夜祭“M－1”への、緊張感も高まります。負けたら同居解消の危機！？ 二人が大舞台に用意した「爆弾」とは…！　文化祭を通して、“許嫁関係”急展開！！　宗一郎の思惑とは。そして、凪が導き出した答えとは！！？