It is a Treasure Tool in the form of a silver tray.
It was created by Gavida, a Crimson Lord who is also the creator of Tendōkyū and Seireiden himself. He enjoyed working and talking with humans but did not want to devour them in order to manifest himself in our world.
Eventually, he built Caina, in which anyone who stays on this wouldn't need the Power of Existence for the manifestation. After the Great War ended and Gavida died, Alastor used this Treasure Tool when he was searching for the successor to the title "Flame-Haired Burning-Eyed Hunter".
- The name Caina may be a reference to Cain, the first murderer in Bible, who was damned into Cocytus, the ninth and last circle of Hell in Divine Comedy written by Dante Alighieri. Noted that Alastor's vessel is also named Cocytus (or Kokytos in Greek). It is unknown why Gavida, who created this Treasure Tool, named it with the name that corresponded to the Crimson God.
|Offensive||Blutsauger • Bubble Loot • Chorde • Dance Party • Hystrix • Kiken no Kentō • Kisan no Taiken • Nietono no Shana • Regular Sharp • Traverso • Trigger Happy|
|Defensive||Azure • Bakuyagai • Orgel • Robe • Tarnkappe|
|Utility||Caina • Crystal Altar • Gehinnom • Giralda • Jettatura • Nine Eternal Divine Scales • Nomenclator • Obelisk • Reiji Maigo • Reshuffle • Saishuku no Shadan • Seireiden • Tendōkyū • Tessera|
|Miscellaneous||Atalante • Nachtigall • Trivia|
|Universal||Gordian Knot • Mekest • Shintetsu Nyoi • Tartaros • Trigon|