Nazo no Kanojo X

Synopsis

After failing to see Urabe in a swimsuit during swim class, Tsubaki sees an image of her in a swimsuit while tasting her sweat. As summer vacation arrives and the two continue their drool swapping tradition, Tsubaki manages to build up the courage to ask Urabe on a date to the beach. A week passes and Tsubaki and a tanned Urabe head to the beach where they eat yakisoba and swim in the ocean. Upon spotting a tanline from Mikoto's pair of scissors, Tsubaki gets a nosebleed which Urabe later experiences when she tries Tsubaki's drool on the way home.

(Source: Wikipedia)