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