Two children, the girl Erika and the boy Satoru, live together in a small house somewhere in modern Japan. One day, before going to sleep, they notice a strange creature outside: it looks like a pink-white cat (Final Fantasy fans would immediately say: a moogle!), but talks like a human being. Before the mysterious creature disappears, it says only a short sentence: "Children! Find the Time Crown!". Without understanding what he meant by this, but realizing it must be something important, the two young heroes embark the next day on a dangerous journey - the quest for the power of the crown!

"Erika & Satoru" plays like a traditional Japanese adventure, although you can also move on the overworld, visiting locations by standing on them and pressing the A button. Upon visiting a location, you can interact with characters and objects you view from first-person perspective by selecting icons located in the corner of the screen: talk to characters, examine, manipulate items, etc. The unusual part is that you control two characters: you can (and should) switch between them and sometimes work together in order to fulfil your quest. There is also a two-players mode, where Erika and Satoru cooperate while being controlled each one by a different player.