For 20 whole years, Ishida and Kimura have been meeting each other once a month, for a weekend in the hot springs, at first as carefree students on their bikes, later - as professionals with busy work schedules, always as friends, month after month. 241 trips. Except, their trips are a secret. Except, neither of them ever married, and nor do they feel lonely because of it. Except, there are unsaid things between them that want to be said...

"Anyone will do. Find me someone who can get married immediately," Yamanouchi Morio said to his senpai, who works for a matrimonial agency. Maybe such a request would not have been so shocking, if it hadn't come from a man who had been a full recluse for the last 10 years. However, his senpai, in his shock, makes a mistake and sends Morio a tall, blond foreign man who doesn't speak a word of Japanese and is running from a troubled past himself...!?

It's a high-tech love triangle! College student 'Yul' Yurugi develops "DD," a conversational AI with the voice, personality, and manner of speaking modeled entirely after himself. To boost its conversational function, he entrusts DD's core to a gentleman expert in AI development. “Your voice is lovely and sweet… I could fall for you.” Yul eavesdrops on their training sessions but, the sweet words addressed to DD felt as if it's him that is being seduced, and his heart is now unwittingly pounding?