Kotaro Ietani, a young boy whose heart is filled with anticipation for his new high school life. On the morning of the entrance ceremony, what awaited him was an unbelievable sight—. "Starting today, your dad is a high school student, too!" Appearing in a school uniform is his 45-year-old father, Ichiro. What's more, his mother Shizuka, his younger sister Haruka, and even his beloved cat Gomez have all become his classmates at the same school! The unprecedented school life of the Ietani family, where every single member has become a high school student, now begins.