The Mystery Tree (quest series)
"The Mystery Tree" is an 'The Island Mystery' quest series with a total of 4 quests and is unlocked after the player has completed the "Stargazing", "Fish Noir", and "Swimming Lessons" quests in addition to reaching friendship level 13 with 
Pompompurin. After completing one of the quests in the quest series, the player must wait until the following day to complete the next quest.
The Mystery Tree: Part 1
Quest Description
"Investigate a mystery tree on the island."
Quest Information
The player will meet 
Retsuko near the Hot Springs in 
Mount Hothead. When speaking to Retsuko, she will tell the player about this odd phenomenon — the tree she is standing near is turning gray and fading! Then the player must speak to the following Island Residents: 
Cinnamoroll, 
Tuxedosam, 
Hangyodon, and 
Badtz-maru. After doing so, the player must then go back to speak with Retsuko, who will be joined by 
Chococat and 
Keroppi.
After regrouping, the player must then go meet Chococat in 
Spooky Swamp, near the Ghost Tour Ride to document other areas around the island. While speaking to Chococat, Retsuko, and 
Kuromi will join the conversation. The player must then do more research around the island by speaking to 
Pochacco and Pompompurin.
The Mystery Tree: Part 2
Quest Description
"Investigate a mystery tree on the island."
Quest Information
The player will meet Retsuko, Chococat, and Keroppi near the Hot Springs in Mount Hothead. When speaking to Chococat, he will explain that the grayness is spreading — alas, detective Badtz-maru arrives! Then the player must speak to Hangyodon at the Comedy Club, regarding a strange blob of 
Dark Water. After which, Badtz-maru has to post about this on his social media page, so the player must then take a selfie with Hangyodon, Badtz-maru, and Keroppi using their 
Camera. After taking the photo, the player must then speak to Badtz-maru. Then, Retsuko will arrive and the player will take a sample of the Dark Water. The player must then give the Dark Water to Chococat at the Hot Springs so he can do some tests.
The Mystery Tree: Part 3
Quest Description
"Investigate a mystery tree on the island."
Quest Information
The player will meet Retsuko, Chococat, Badtz-maru and Keroppi near the Hot Springs in Mount Hothead. When speaking to Chococat, he will indicate that one of the trees nearby is resistant to "The Fading" and tell the player to bring the Dark Water to the tree — once doing so, the Dark Water will turn into 
Mysteriously Clear Water. A bit later, it will turn back to "Disappointingly Dark Again Water". Keroppi will then mention that the light shining on the resistant tree is shining down from 
Cloud Island.
Retsuko, Chococat, Badtz-maru, Keroppi, and the player must then travel to Cloud Island to speak to 
Kiki and 
Lala. Kiki will tell Badtz-maru he must be paid in 
Starry Skies Shakes in order to help with the investigation. The player must then give Kiki a Starry Skies Shake. Once doing so, everyone will walk over to the 
Cloud Router, where Kiki will explain that one of the parts has broken off. The player must then meet Chococat near the Hot Springs in Mount Hothead and give him 10 
Starfruit and 10 
Moon Cheese. Once doing so, he will begin to work on a solution!
The Mystery Tree: Part 4
Quest Description
"Investigate a mystery tree on the island."
Quest Information
The player will meet Retsuko, Chococat, Badtz-maru and Keroppi near the Hot Springs in Mount Hothead. Chococat will tell the player that he has created a 
Cloud Core, but he still needs a few more additional items to craft the
Cloudlight! The player must then gather the materials to create the Cloudlight, which include: 20 
Lotus Blossom, 20 
Magma Bloom, 20 
Sakura, and the Cloud Core.
After crafting the Cloudlight, the player will then go speak to Chococat at the 
Resort Gate crafting table. Next, everyone will go to the Dark Water near the Comedy Club. The player must then use the Cloudlight on the Dark Water, which will then reveal the Cloud Router. After the player picks up the Cloud Router, the player must then speak to Badtz-maru, where he will mention his suspicions about the 
LittleTwinStars.
The player must then bring the Cloud Router to Kiki and Lala, and gift it to Kiki. Kiki will then repair the Cloud Router; however, it will begin to malfunction! 
Big Challenges will then tell the player that 
TOPHAT is in trouble. The player must go speak to TOPHAT, who will start looking distressed and mention that he's being overloaded with memories, before saying, "Before she... fades..." and finally disappearing. Retsuko will then say, "The island... is alive?" and Keroppi will explain that the island is who needed our help all along!