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