Thanawat Singsomboon or "Thana" (Sehun of EXO/Jang Hyuk) and Kunchanita Sasirikorn or "Nita" (JooE of Momoland/Jang Seo Hee) became unmarried parents at a young age even they were still high schoolers. However, due to circumstances happened unexpectedly, Nita raised three sons (namely Hannarong Sutthiphong, Sutthiphong Hannarong and Rinedhep Sutthiphong; played by Lee Seo Jin, Lee Byung Hun, and Hyun Bin) healthily but grown-up in a romantic relationship between brothers. Even their family life was tested by circumstances,  togetherness still unites them despite from thick to thin, and sickness and in health.