She disguised herself as a cute Japanese schoolgirl who teases Beast Boy by calling him an "otaku", which Beast Boy thought meant cute (it actually means "geek" or "nerd"). Thinking she was calling him cute, Beast Boy fell in love with her and chased after her and was lead into a karaoke club.
Later on, she revealed her true identity and fought Beast Boy to keep him from helping Cyborg, easily defeating him by distracting him. Like the other Titans, Beast Boy barely escaped the battle.
Nya-Nya was cloned many times when the Titans were fighting against Brushogun's creations. After Uehara Daizo was defeated, she disappeared along with all of the other ink creations Brushogun had created.
Power and Abilities
Super Strength: Nya-Nya has incredible strength as she defeats Beast Boy in T-rex form and busted open a vending machine with her feet.
Acrobatics: Nya-Nya has extremely good acrobatic skills.
Martial Arts: Nya-Nya has incredible martial arts skills; almost surpassing those of Robin's.
Shapeshifting: Nya-Nya can disguise herself into any form she wants.
In her Human Form: (giggles) "Otaku" (giggles) (Otaku is the honorific word of Taku, (home).
While fighting Beast Boy: "Kawaii dobutsu o shitsukeru no daisuki na no! Ureshii wa, Anata o ijimeru no ga tanoshimi!" ["I love training cute animals! I'll be happy to torment you!"]
After Kissing Beast Boy: "Me o tojite, (giggles) itai wa yo. ["Close your eyes, (giggles) this will hurt."]
Nya is the Japanese onomatopoeia for the sound a cat makes, just as meow is in English.
It has been confirmed that the name for Nya-Nya's human disguise is Miko Tezumi by Glen Murakami based on a foreign exchange student from his college days in which he had a crush on.
Nya-Nya is one of the most popular characters in Trouble in Tokyo as many people have made their own fan art, stories and more. She is considered the most popular out of all of Brushogun's creations.
She only speaks Japanese, unlike most Japanese characters in Trouble in Tokyo who speak English in stereotypical Japanese accents. (unless the actor's are actually Japanese or Asian, then it's not Stereo-typing), other than that who knows.
Her design is a parody of the stereotypical catgirls that often appear in anime.
She could have a crush on Beast Boy as she kissed him during the fight, or she could have used it to stall him.
Her hands resemble that of Pantha's, having clawed/pointed fingers.
Nya-Nya's eyes are closely similar to Jinx's, being pink with cat pupils.
It's possible that the first Nya-Nya gets defeated/"killed" by Cyborg because he mentions Beast Boy as the only Titan that was defeated and he was the closest Titan here.