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