2) Simple and Clean by Utada Hikaru is the theme song of the game. Did you know that it is also the main theme of some Kingdom Hearts games, namely: Kingdom Hearts, Kingdom Hearts Chain of Memories and Kingdom Hearts Re:Coded.
3) An exclusive game titled Kingdom Hearts Birth by Sleep Final Mix was released in Japan on 2011 for PSP handheld console. It is basically a reissue of the original game, but has several additional features such as new bosses and new matches in the Mirage Arena.
4) It is interesting to note that the number 13 has always been a recurring number in Kingdom Hearts series. In Kingdom Hearts Birth by Sleep, there are exactly 13 matches in the Mirage Arena excluding the additional matches from the Kingdom Hearts Birth by Sleep Final Mix version.
5) There is a code in Kingdom Hearts Birth by Sleep Final Mix that was added to be used for Dissidia 012 Final Fantasy game. It unlocks an alternative costume for Cloud Strife.
6) Zack Fair is originally a Final Fantasy character that was introduced in Final Fantasy VII. He is the main protagonist of Crisis Core Final Fantasy VII.
7) Did you know that the Olympus Coliseum appeared in almost all of Kingdom Hearts title? So far, it is only in Kingdom Hearts 3D: Dream Drop Distance that the place was not featured.
8) Although it is featured in North American and European release, the Critical Mode difficulty level is originally not present in the Japanese version of the game. Nevertheless, it was added later in Kingdom Hearts Birth by Sleep Final Mix.
9) The name Zack is usually used as a shortened form for "Zachary," "Zachariah" or "Zacharias." It is a Hebrew masculine name, which means "remembered by God."
10) Ironically, Hades and Pluto are both names of one single deity in Greek and Roman mythologies. He is the ruler of the underworld and the brother of Zeus.
11) Aeleus' name is slightly changed as "Elius" in the North American version of Kingdom Hearts II. Nevertheless, the official name given to him in the canon is still Aeleus.
12) The weapon that Aeleus wield is called an Axe Sword. Contrary to what its name suggests, it looks more of an axe than a combination of two weapons.
13) The name Ventus is probably taken from the Latin word which means "wind."
