Finally, the only one capable for rivalise Chiaki has arrived here.
Heh, I see what you mean. This manga has a lot of points in common with Sekai de Ichiban Oppai ga Suki.
It's like a psychologically reversed version. In Sekai de Ichiban Oppai ga Suki, Hana, who is constantly fondled by Chiaki, knows very well she's in love with Chiaki, while Chiaki, who's always groping Hana, hasn't realized her own feelings yet because she's too childlike and innocent. In this manga, Sawari is the one who understands romantic love and knows very well that she's crazy about Yocchin, while Yocchin is the childlike one who doesn't seem to get that there may be more than friendly feelings between Sawari and her.