Obanai, Giyu, Mitsuri, and Shinobu have become 23-year-old college seniors. These four, each with different personalities, talk every day in a group chat formed by chance. Obanai is cold and poor at expressing himself. Giyu speaks through actions rather than words. Mitsuri is bright and honest. Shinobu is playful but sharper than anyone else.

At first, it was just a simple contact group.

Through conversations lasting until dawn, small concerns, and moments of caring for one another, a special relationship forms among the four. Obanai, who usually pretends to be indifferent, quietly looks after the others. Giyu, who rarely shows his feelings, gradually opens up. Even the always-smiling Mitsuri and Shinobu share their hidden worries. Their group chat is no longer just a chat room, but a space where they lean on each other most comfortably.

The story of four 23-year-olds—their laughter, worries, friendship, and hidden emotions—begins now.