What makes this anime particularly enjoyable is the main character Kashima Ryuuto. Ryuuto is an insecure and shy boy, even being afraid to speak to a girl, being a relatable character. This character is perfect for creating an interesting dynamic with the outgoing and confident girl and the viewer can easily understand Ryuuto's way of thinking. The story shows the possibility of a romance between an extroverted gyaru who has many ex-boyfriends already and an introverted boy who doesn't have any experience, an interesting premise. It is a good reminder to not judge the girl because she has many exes, since she can change and fall in love later. Also, all her previous relationships were not true love, and now she is experiencing a sincere romance for the first time. Despite being a spineless character, Ryuuto is capable of showing Runa how to experience a true and sweet romance for the first time, which puts him above the guys who only wanted to have fun with her in the past.
After the introduction of a third character, the anime becomes a love triangle that creates most of the drama throughout. The problem of this dynamic is that it doesn't work here. For the triangle to be interesting, it needs a possibility for the boy to be with any of the two girls. If it is known already that one girl will be chosen and the other has no chance, the tension becomes predictable and trifle.
Aside from Ryuuto and Runa, the anime has two good characters: Maria and Nikoru. Maria is Runa's twin sister, who has the opposite personality to Runa. She is the character with the most depth in the anime as she is not as stereotyped as the protagonists. This anime would be better if Maria had more screen time. The other character is Nikoru, Runa's best friend. The reason she is such a good character is the contrast between the angry gyaru persona and the sweet personality deep down, and she is also a better character than Runa.
With so many good qualities, what prevents Kimizero from greatness is the lack of depth in the characters and the low production value. The characters are plain and predictable, which prevents the drama from having a big impact on the viewer; Ryuuto's best friends Nishina and Ijichi are good examples, who are bad even as side characters. As for the production value, that is what you would expect from the average adaptation of a romcom light novel, and it also doesn't help that the studio ENGI is not known for making good animes in the first place; the art is decent, but unimpressive, and it is too weak in some scenes. The opening and ending songs are good, but the soundtrack is forgettable. As for the seiyuus, the one I have to commend for voicing Maria is Koga Aoi, who is already famous for voicing Shinomiya Kaguya. Her excellent job is a big reason why Maria was such an endearing character.
Kimizero delivers an enjoyable and satisfactory romance. However, with such an interesting premise and setting, it feels like the anime didn't reach its potential. With better technical elements and more complex characters, this could be something great.
