Mystery Time is a period of time that occurs before each new mystery that a player must solve, and can be triggered once a week. It can be activated by either using the Mystery Key on the Gate of the Beginning of the End, or be automatically triggered by a certain date. According to Principal Sol , only human children can activate Mystery Time.
During mystery time special types of Insects and Fish can be found that can not be caught at any other time. This includes creatures such as the Mandragora, the Vampire Squid , and others. Mr. Graves will also give Extracurricular Classes in The Plaza during mystery time.
Mystery time lasts for one full in-game day. Upon it's end things return to normal and a Mystery Quest will begin.