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
Meet Draculea
Draculea's Secret
Get all stars from Draculea
Kinutanuki's Secret
Get all stars from Kinutanuki
Meet Kinutanuki
Get all stars from Amanozako
Meet Amanozako
Amanozako's Secret
Kawauso's Secret
Get all stars from Kawauso
Meet Kawauso
Akakami's Secret
Get all stars from Akakami
Meet Akakami
Use a hint in game
Kurage's Secret
Get all stars from Kurage
Meet Kuragenohinotama
Kinoko's Secret
Get all stars from Kinoko
Meet Kinoko
Ouni's Secret
Get all stars from Ouni
Meet Ouni
Ungaikyu's Secret
Get all stars from Ungaikyu
Meet Ungaikyu
Open the friend book(please install free DLC)
Ichiko's Secret
Get all stars from Ichiko
Meet Ichiko
Kuda's Secret
Get all stars from Kudagitsune
Meet Kudagitsune
Get all stars from Atake
Atake's Secret
Meet Atakemaru
Kane's Secret
Get all stars from Kane
Meet Kanedama
Neko's Secret
Get all stars from Neko
Neko's Magic
Meet Neko
The Story
Yokai's Encounter