Cinnamoroll is Missing
"Cinnamoroll is Missing" (formerly known as Suspicious Sounds) is an 'Friendship Quest' quest that is unlocked when the player reaches friendship level 14 with 
Cinnamoroll and has completed the "Delivery Service" quest.
Quest Description
"Investigate the source of the suspicious sounds."
Quest Information
The player will meet 
Hangyodon at the Comedy Club fast-travel point. Once talking to Hangyodon, it will be revealed that the sounds have been coming from Cinnamoroll, who is stuck inside. Cinnamoroll will then ask the player to find his 
Mailbox Key, located on the plane.
He will give the player an 
Propeller Hat, to be given to the 
Nul, standing next to the Resort Plaza fast-travel point. After the player gives the Nul the Propeller Hat, they can ask the Nul to transport them to the plane. The Mailbox Key will be located near the back of the plane. After returning the Mailbox Key to Cinnamoroll, the player will be given a Propeller Hat and have unlimited access to the plane.
