Ninja Gaiden Sigma Plus

Missable!
Just save your essences until you reach 99,999 yellow essence. Very easy if you're farming.

If you're planning to farm essences, then the best places to farm is Chapter 12 and 18. Bugs and Ghost Fish die very easily and if you kill them without taking damage you will get bonus essences. Chapter 18 is the fastest since you can accumulate 7-8k per minute if done properly. From 0-99,999 should take 15-20 minutes.