ココロインサイド is an iPhone game developed by SYUPRO-DX Inc. It is a free game in the Games category. In this game, the main character returns to their childhood town after many years and reunites with their old friend. They come across an app that allows them to dive into people's hearts. Little did they know, every person's heart is inhabited by "Mamono" or creatures. The game revolves around exploring the hidden truths and secrets within people's hearts.

The story takes place in a town that was once filled with cherished memories but is now plagued by mysterious disappearances. Female high school students are vanishing one after another, and the town has earned the reputation of being the "City of Disappearing People." The player must navigate through these strange occurrences and uncover the truth hidden within people's hearts.

ココロインサイド offers a unique and immersive adventure, allowing players to experience the thrill of diving into the depths of the human psyche. With its captivating storyline and intriguing mysteries, this game is sure to keep players engaged for hours.