Riichi, who is known as the frigid cold man, is an expert bodyguard who leads the security team in charge of a conglomerate's son. One day, he got appointed to mentor Tachibana, a skilled guy whose background information is unknown, and that very same day Tachibana said he used up all his paycheck and doesn't have a place to stay. Ended up mentoring Tachibana both at work and private time, started the days of Riichi being at a loss over how to deal with him. Moreover, Tachibana seems to like him from their first meeting and tries to flirt with him day and night…?!Unpredictable Newbie x Cool Beautiful Senpai, an epic love story between an odd pair!