Lead female of the series and Tsukune's genuine love interest.
Moka and Tsukune meet, innocently enough, when Moka loses control of her bicycle and crashes into his back. While getting back up Tsukune accidentally grabs her leg most of the way up the thigh. After a brief moment where Tsukune is mystified by how cute she is the poor guy realizes where his hand was and flails away shouting in a typical anime fashion "I'm sorry!!!" about two dozen times. In another purely anime moment, his nose starts to bleed. Moka, being a kind individual, grabs her handkerchief and begins to stop the bleeding but is overcome by an impossibly good "smell". She apologizes... and bites his neck. Leaving a mark that looks remarkably like a hicky.
When they both arrive at the school proper (Moka innocently admited to being a vampire and asked Tsukune to be her friend... awww) she is delighted to find out that Tsukune is in the same class as her. And immediately starts to make things difficult for Tsukune, although not intentionally. Her merely paying so much attention to Tsukune automatically garners him the animosity of every eligable bachalor in the school. Shortly after class she finds Tsukune up on the school roof, she shows him the rosario on her chest (Tsukune assumes that she was going to show him her breasts and panics accordingly), revealing her true nature. The first episode culminates in the revealing of what happens when Tsukune removes the rosario, releasing "inner" Moka (more on her later) and inner Moka takes down an orc in one kick.
Fast forward to Kurumu's entrance. Moka becomes VERY agitated when a blue-haired girl comes and is seemingly able to steal Tsukune away at will. Moka dwells on this until she realizes that Kurumu is a succubus. She then arrives just in time to stop Kurumu from enslaving Tsukune. Prompting a weakened Tsukune to fall off of the bed and grab Kurumu's panties on the way down (completely by accident... we hope). Long story short, Moka kicks Kurumu's butt and Kurumu falls for Tsukune when he defends her from Moka.
Next episode, a little girl is being harrassed by three older boys, Moka once again sticks up for someone in danger. This little girl then claimes to have fallen in love with Moka (......creepy......), this little girl is a witch named Yukari. How Moka is able to put up with Yukari hanging from her breasts while she is walking down a hallway is a complete mystery to me. When Tsukune judges Yukari it is Moka that forces him to question how he looks at the little girl. Moka inadvertantly increases her competition again by saving Yukari.
Fast forwrad, Moka saves Tsukune from being frozen and taken by Mizore. This prompts a huge investigation that clears Mizore's name and adds another love rival for Moka (she seems to have a bad habit of adding to Tsukune's problems by being so nice).
Now I will delve into her personality. Moka is, to put it simply, kind. So kind to the point where she is almost a pushover. Also, her love of Tsukune could typically be considered the most "pure", although one might argue that she drains his blood far too much causing the screen to go black with nothing but a pink "kiss" sign in the center with the adorable sounding "kapuchu!!!". As she goes to great lengths to help him when he is down or depressed. She is also very forgivng of others for their mistakes (like Yukari and Ruby). The only drastically annoying parts of the anime is the moments that occur in EVERY episode where Tsukune and her are simply staring at each other with a glittery pink background and sappy music playing.
Here I must describe the other side of Moka that is revealed by the removal of her rosario.
The "inner" or true Moka has a completely differant personality to the one that is present for the most time. Even differing in physical appearence (let's just say that she is more physically attractive, larger breasts, bigger butt...) with silver hair and red eyes. Also has a trendency for kicking things with rather impressive flexibility (thing is that she flashes her panties every time she does). At first, this inner Moka is vehemently against Tsukune being in the life of her shared body, predictably though, the inner Moka starts to change her mind after witnissing how far Tsukune would go on her behalf. This inner Moka is the one that is always beating up the antagonist of the episode. One last interesting note, while the pink-haired Moka gets very put off by the other girls massaging Tsukune with their breasts, inner Moka joins in (although at the same time terrifying everyone else involved). Towards the end of the second season inner Moka gets significantly more screentime after the pink haired Moka sarcifices her rosario to seal off the school from the human world. This prompts the inner Moka to try and take the other Moka's place, explaining to Tsukune "this is the same person that you care for". Sadly, for inner Moka, Tsukune is not convinced and instead, challenges Moka's father, one of the "Hades Kings" to get a new rosario for Moka. Just before being sealed again inner Moka imitates her pink haired counterpart by drinking some of Tsukune's blood, in a deeper (sexier) tone of the "kapuchu!!!" from the other Moka.