i think second or third, the second one proves that he's loved her a long time but was too '' haughty'' to tell her, the third is like him confessing that he loves her and wanted her.
2nd or 3rd, because for the second one, it proved that he loved her, and for the third one, because he didnt want her to tell him that she loved someone else.
eek, so cute!
Second one is the most romantic. First one he did just to tease her, the second one was done in secret to express his feelings for her in a way that not even she would know.
i love the 1st one though hahaha
although most people say the 1st kiss was meant to be a tease..
but i think irie purposely kissed kotoko so that she can't dare forget him...
the 2nd and 3rd kiss were also my fave... but i think 1st one for me
outshines all the kisses