How many levels of tour strings unlock tour groups?

The fifth floor "Travel String" is a casual simulation game that warms and cures the wind. According to official website, whoever inquires about the game has five levels in the system to unlock the tour group, and then you can join other players' tour groups accordingly. This game is designed in cartoon style and has a warm scene. In the game, players need to help a couple complete their yearning trip by selling strings, and the gameplay is very rich.