Naoya Mukai is having the time of his life after his childhood friend Saki Saki finally accepts one of his countless confessions. Ensuring that their relationship will stay strong, he spares no effort in showering affection to his now beloved girlfriend. However, one afternoon, another girl named Nagisa Minase suddenly confesses to Naoya following months of preparation. Even though he politely rejects her, Nagisa's irresistible charm and determination continue to attract Naoya. Wanting to fulfill both Saki and Nagisa's desires, Naoya ends up proposing a crazy idea—to date the two of them simultaneously, with both girls fully aware. This unprecedented state of affairs ultimately causes wacky and hilarious situations in whatever they do to keep their unusual relationship going.

Following their trip to the hot springs, Naoya decides to continue his two-timing relationship with Saki and Nagisa, and will treat them fairly. Add to the mix, Mirika who kissed him first, and Shino who has a secret crush on Naoya. The stage is set for the five lovebirds as summer vacation arrives. Fireworks, camping, and then to Okinawa... Mirika's younger sister, Risa, also makes an appearance. The neo-standard love comedy gets more and more exciting!