IIn the Bleach series, Bankai is the term used to describe a technique by some captains and higher-ranked Shinigami to attain a higher state of being. The word “Bankai,” meaning “second form” in Japanese, is used to mark the transformation of Zanpakuto into its second most potent form.
When Shinigami use this technique, they are said to have “transcended the mortal coil.” As with most things in life, you get out what you put in, which is no exception for Shinigami. There are many different types of Bankai.
Some are more powerful than others, and some are only accessible by certain kinds of Shinigami.
You might wonder what makes one type of Bankai more potent than another. It all comes down to preference. There are many different ways to fight and many different ways to win.