Here is the full list of all 24 Samurai Riot achievements.
Kill the rebel leader
Join the rebellion
Kill your sister
Join your sister's fight
Seal the Torii
Leave the Torii open
Bring peace to the land
Slaughter the samurais
Commit seppuku
Honor your dept to your family by killing your master
Set Makoto on the throne
Crush Makoto and give the power to the people
Wage war against the Yokais
Put down your swords and talk some sense into these Yokai
Unlock the 8 endings of the game
Unlock all the golden medals of the game in Easy mode
Unlock all the golden medals of the game in Normal mode
Unlock all the golden medals of the game in Hard mode
Unlock all the golden medals of the game in Hardest mode
Unlock all Sukane's schools
Unlock all Tsurumaru's schools
Recruit the blue kitsune
Get in a PvP fight
Win Azu's second tail