During a meal with the usual close-knit group—consisting of four members: ‘Haru’ (Spring), ‘Natsu’ (Summer), ‘Aki’ (Autumn), and ‘Fuyu’ (Winter)—Aki suddenly murmured a single phrase, “I want a childhood friend.” As a result of that utterance, ‘Natsu’, who often hangs out with ‘Aki’, undergoes a complete transformation in her behavior!? From sharing lunch breaks to making appealing displays in swimsuits during swimming lessons! And even going so far as to come to his house in the morning—an onslaught of full-force appeals! ‘Haruna’ and ‘Fuyuki’, a pair of close friends, get involved as well. And thus, this summer, the relationship of the four close friends—’Haru’, ‘Natsu’, ‘Aki’, and ‘Fuyu’—underwent a significant change.