Here is the full list of all 30 Ritual Tournament achievements.
Win a fight with Nai-Yn
Win a fight with Sayaka
Win a fight with Atsuka
Win a fight with Hanzashi
Win a fight with Nariko
Win a fight with Kaya
Win a fight with Nagisa
Win a fight with Keyla
Watch the Credits
We know you are eager to spill some blood
Perform a Sacrifice with Sayaka
Perform a Sacrifice with Hanzashi
Perform a Sacrifice with Nai-Yn
Perform a Sacrifice with Atsuka
Perform a Sacrifice with Nariko
Perform a Sacrifice with Keyla
Perform a Sacrifice with Nagisa
Perform a Sacrifice with Kaya
Reach the Alternative Ending
Reach Nai-Yn Ending
Reach Sayaka Ending
Reach Nariko Ending
Reach Atsuka Ending
Reach Nagisa Ending
Reach Hanzashi Ending
Reach Keyla Ending
Reach Kaya Ending
You did exactly what she wanted
Finish the game on Hard Difficulty (any ending)
Reach the Game Over screen