The TsunderePhoto: Tokyo MX
Examples of The Tsundere: Chitoge from Nisekoi (pictured above), Yui Kotegawa from To Love-Ru, and Haruko Amaya from Maken-Ki.
Who They Are: Tough on the outside but soft on the inside, the Tsundere very obviously likes the MC (main character) but covers it up with embarrassment, and usually a punch to face. Since most MC's are incredibly dense, they can't see how obvious the Tsundere's feelings for them are.
This leads to endless bickering – usually accompanied by exclamations of idiot – which paradoxically brings them closer together. After everything, the Tsundere usually has the best chance of ending up with the MC.
The Childhood FriendPhoto: Tokyo MX
Examples of The Childhood Friend: Yuki Nonaka from Testament of New Sister Devil (pictured above), Irina Shidou from High School DxD, and Rei Miyamoto from Highschool of the Dead.
Who They Are: Kind, compassionate, and usually an excellent cook, the Childhood Friend is a formidable opponent to the rest of the harem since they've known the MC longest. Very much the girl-next-door type, the Childhood Friend is generally liked by other males in the series, who can't understand why the MC has never noticed how amazing she is. Despite how close she may be to the MC, her chances of ending up with him are exceedingly low, most of the time regarded as a sibling rather than a love interest.
The Lewd OnePhoto: TBS
Examples of The Lewd One: Rika Shiguma from Haganai (pictured above), Akeno Himejima from High School DxD, and Momo Belia Deviluke from To Love-Ru.
Who They Are: The most sexually aggressive of the bunch, this girl is not afraid to get down and dirty with the MC (or the other girls for that matter). Their humor and dialogue tends to be filled with innuendo, and she loves teasing the other girls whenever she has the chance.
She often uses her sexual confidence as leverage for her candidacy as the MC's end girl, but is usually more comic relief character than anything else. This girl doesn't have a high chance of ending up with the protagonist. However, she certainly gives the other girls a run for their money when it comes to who can kiss the MC first.
The Sweet And Innocent OnePhoto: TV Tokyo
Examples of The Sweet and Innocent One: Lilith Asami from Trinity Seven (pictured above), Haruna Sairenji from To Love-Ru, and Kosaki Onodera from Nisekoi.
Who They Are: The exact opposite of the the Lewd One, the Innocent One is embarrassed easily and prone to tears. They are generally naive and very shy when it comes to their feelings, but unlike the Tsundere who acts out harshly, this type will simply blush hard and wave her arms around frantically.
Though she wants desperately to be with the MC, she may not garner the courage to express her feelings, despite how obvious they are. This type's caring and kind personality makes the likelihood of her being chosen incredibly high, as long as the guy has the guts to express his feelings first.