The *(star) level is The World Ends With You is the highest rank that can be obtained in the game. This star is used for in game battles, where it ranks you upon performance and gives you either numerical rankings, or if one is good enough, a star. The star is also used to show pin mastery as a pin levels up, instead of evolving it will take on a star and its bar will become orange, meaning it is mastered and at its highest potential. The same could be said for Neku's level - level 100 is actually the * level, instead of being numerical, since one cannot go any higher.
Along with the numerical rankings it battle, the star is also the rank a person gets if their stats are 100% worthy. So getting 96 pages of noise out of all 96 would be rewarded with a 100% mark, the *.
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