How to get the S rank
Your actions during the game determine how many points you´ll receive at the end and you´ll need over 41 of these to get the illustrious S rank. Here´s a quick list of everything you need to do in game to earn maximum pointage.
Miscellaneous
Points +10 - Finish the game i less then 6 hours
Points +10 - Absorb over 170,000 souls
Points +10 - Kill more then 2,300 enemies
Points +10 - Perform over 600 critical or counter crotocsl attacks
Points +10 - For every Dark Realm sidequest completed
Completion Time
Points +10 - Finish in 5.59 hours or less
Points +06 - 6:00-7:59
Points +04 - 8:00-10:59
Points +03 - 11:00-13:59
Points +02 - 14:00-16:59
Points +01 - 17:00 hours or more
Dark Realm
Points +10 - For each of Samanosuke´s secret weapons
Points +10 - Pick up Ako´s purple vest
Points +30 - Acqurie Samanosuke´s Bishamon
Points +30 - Get Jacques Musou whip