Here is the full list of all 31 TOKOYO: The Tower of Perpetuity achievements.
Collect 101 log pieces
Get hugged by a Succubus 5 times
Achieve 20 bonus score chains
Defeat the Immortal Nanaha
View ending with Kanae
Defeat Riim the Irreversible End
Collect 50 log pieces
View ending with Shippo
View ending with Kukuri
Reach the summit three days in a row
Defeat the Demon Queen Erloa
Get your blood sucked by a Vampire 5 times
View the ending with Cocoa
Reach the summit two days in a row
Collect 25 log pieces
Get hugged by a Maid Succubus 5 times
Climb 250 floors
Reach maximum karma
Collect 10 log pieces
View ending with Imibi
Defeat Lula of the Dark Star
Climb 100 floors
Climb 50 floors
Reach the Absolute Danger Area
Reach the Hopeless Area
Reach the Unknown Hopeless Area
Climb 25 floors
Achieve 10 bonus score chains
Reach the Light Danger Area
Reach the Danger Area
Achieve 5 bonus score chains