Here is the full list of all 49 Yokai's Secret achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Yokai's Secret
Get all colors back
Draculea's Secret
Get all stars from Draculea
Meet Draculea
Kinutanuki's Secret
Get all stars from Kinutanuki
Meet Kinutanuki
Get all stars from Amanozako
Amanozako's Secret
Neko's Magic
Meet Amanozako
Get all stars from Kawauso
Kawauso's Secret
Meet Kawauso
Akakami's Secret
Get all stars from Akakami
Meet Akakami
Get all stars from Kurage
Kurage's Secret
Meet Kuragenohinotama
Get all stars from Kinoko
Kinoko's Secret
Meet Kinoko
Ouni's Secret
Get all stars from Ouni
Meet Ouni
Get all stars from Ungaikyu
Ungaikyu's Secret
Meet Ungaikyu
Ichiko's Secret
Get all stars from Ichiko
Use a hint in game
Meet Ichiko
Get all stars from Kudagitsune
Kuda's Secret
Meet Kudagitsune
Open the friend book(please install free DLC)
Atake's Secret
Get all stars from Atake
Meet Atakemaru
Kane's Secret
Get all stars from Kane
Meet Kanedama
Neko's Secret
Get all stars from Neko
Meet Neko
The Story
Yokai's Encounter