Tantei Jing?ji Sabur? ~ Mikan no Rupo is a Japanese style adventure game in the detective/mystery genre. It is the 5th game in the Jake Hunter / Tantei Jing?ji Sabur? series, being released between Toki no Sugiyuku Mama ni... (1990) and Yume no Owari ni (1998). While following the same formula of the previous titles, the game features a "Zapping System", allowing the player to see the story from the perspective of other characters as well as Jing?ji. Also featured in this title is car chase and following suspects in the form of 3D mini-games, although these features would rarely be seen again in future releases.

One day, an air mail arrives in Jing?ji's office. The sender was a drinking friend of Jing?ji's named Ikegami, the package contained a key that seemed to be from a coin locker. As the detective investigates cases of missing persons, drug dealings, and murders, the mystery of the key is gradually revealed. Now the famous detective has to follow the leads left by his friend and avoid the traps cleverly set by his enemies.