Inumaki Toge and Okkotsu Yuuta first met when they were seventeen, both natives of Sukuna Island, a small community off the coast of Japan. Circumstances forced them apart for four years. The last thing Yuuta had gifted Toge was a 500-page notebook meant to be used for letters to Yuuta while he was away. Unfortunately, the plan fell through. When they finally reunited, they found that much had changed, but the island itself remained the same.