Under the light of a full moon, bartender Aki meets Moka, a young office worker from Tokyo. But then Moka receives her own diary entry.

The two men each plan competing dates in Tokyo. Aki lives in the metropolis, so he might have an advantage over Koyo, who's a med student in Nagoya.

Moka, Aki and Koyo set out on their three-day trip together. Then one of the men gets a diary entry that tells him to wear a cupid's bracelet.

The three put together a Halloween party, but Moka is nowhere to be found. Aki and Koyo go out into the cold night to look for her.

Moka, Aki and Koyo depart for a trip to Shodoshima. The three have become close, but soon, Moka will have to say goodbye to one of the men.

Aki still feels like the underdog, but on the second day of the trip, he hopes to turn things around during his one-on-one date with Moka.

Early in the morning on their last day at the island, Aki and Koyo wait for Moka to reveal her final decision. Later, a tearful farewell unfolds.

Six days after their bittersweet trip to Shodoshima, Moka and the man she chose spend some time as a couple by Lake Kawaguchi.

The couple knows that the end of their love story has been decided. As the minutes wind down, Moka recalls how special their time together has been.