Jotaro the Marine Biologist is the Guide of JoJoStands. Jotaro's main use is to give new players the Arrow Shard, which players can get by talking to him and pressing "Stand Help". He can also tell you about the abilities of the Stand that is currently placed in the Stand Slot, and if no Stand is currently placed in the Stand Slot, he will give you useful information about certain unseen and easy to miss functions.
Jotaro can spawn as long as there's a vacant home in the world. He may take a while to spawn but as long as you have an empty house he will spawn
When an enemy comes within range, Jotaro brings out Star Platinum. Star Platinum performs attack rushes and barrages on enemies near Jotaro, and if no enemies are near him after 7 seconds, Jotaro retracts Star Platinum.