Final Fantasy--Last Boss

At the end of every FF game, there is always an end-boss for the protagonists to defeat. Usually, the big bad guy refuses to die in just a single fight and will linger on in different polymorphs.

In this story, our main character has reached the end of the game. After levelling up to the maximum level (usually 99 or 100 by convention), the party approaches the series of bosses.

Weapons sharpened, stats maxed. The ultimate of every item is obtained. (at least in my FF games, almost). What is unusual is that the main char is alone facing the bosses.

There are 5 bosses altogether. Two come together, the rest come in alternate days. Let's enjoy the ending credits by the end of May.