Let's start with Aya. I don't like her, plain and simply. She falls for the mc from the very beginning but never acts upon it until the very end. Yes, Manaka helped her out of her shell, made her fell more confidence about her writing and shared his dream that she accepted as her own. And that's it. Their exchange is limited to that. All this receives no further development other than Aya finally realizing she has her own path in life to follow. She felt kinda pathetic.

I have few things to say about Satsuki. When she appeared at first I liked her character. She was very outgoing, aggressive even and her relationship with Manaka builds over time with them having similar tastes. But then, a disaster. She uses only her body to seduce him. Her aggression spills over and she strips naked in front of him, forces herself on to him, even tries to rape him couple of times. So Satsuki surfaces as a one trick pony she is and builds my dislike towards her. Mangaka even tried to drop her from the race two time always bringing her back like she couldn't figure out what else to do with her afterwards.

Now the main course, Tsukasa. For me the most enjoyable character of the entire series. She's not too passive and not too aggressive and falls down the middle of the previous two. She is nice but not lenient like Aya, has backbone and tends to speak her mind but is not overly obtrusive like Satsuki. With Manaka Tsukasa is both kind and harsh at times but always showing her love and loyalty. At one point she dumps him but soon comes back and is ready to wait for him to make up his mind. Not that Manaka did anything to deserve this but whatever.

All this being said, the ending didn't came as much of a shock really. I read other people comment's and was quite surprised to see many readers not expecting it. I pretty much dropped Aya as a likely candidate to end up with mc early in the series. Doubt about this prediction did surface in the last couple of volumes but throughout the series I gave more chances to Yui than Aya. As I mentioned before, her and Manaka's relationship receives no development. They like each other from the start but neither does anything about it. You need more than initial liking for relationship to works. Many people think that they were fated to be together but that is stupid. I am honestly glad that fated couple/number thing at the festival didn't get further advancement. That would be moronic. Opposite to this you have Tsukasa who took more active role. She didn't seek to get close to Manaka by following him to the same school. She took her time with him, going slowly and building up and coming out on top by showing great character development. Even her ecchi scenes served to a purpose of advancing their relationship, unlike the others'. Had Manaka ended up with some other girl all that build up would be in vain. The ending itself was classical "x years later" type. It has a small degree of openness to it. Manaka is still on his way of becoming a successful movie director and his relationship whit Tsukasa starts over with their future relying solely upon them. I tend to like it.

First and ONLY Person Manaka ever Dated - NISHINO
First and ONLY Person Manaka ever Kissed - NISHINO
First and ONLY Person he made a congressial Date with - Guess who?

i personally like Aya with Manaka, since i think they have the same "aura"
and i really like the way they "wishy washy thing", their undecided habit, and a lot of thing about Aya and Manaka

the author just abandoned Satsuki at a certain point. In the last chapter she actually says that she likes Toujo and Nishino ¬¬

it was perferctly developed for a Nishino Tsukasa ending