|Name (Kanji)||渡瀬 伸吾|
|School||Yamaboshi High School|
2-B (Post Michi Random)
|Homeroom Teacher||Gotou Ryuuzen|
|Seiyū||Ono, Yuuki (小野 友樹)|
|Novel Debut||Volume 2, Chapter 3|
|Anime Debut||Episode 2|
|“||Are you some kind of masochist?||”|
Watase is shown to be fairly self-confident and has a mischievous sense of humor. Watase enjoys teasing Taichi about his love life and occassionally expresses slight jealousy over how popular his friend is with girls, but otherwise has proven to be a loyal and caring friend.
Despite supposedly being a fairly bright student, all traces of such are hard to notice when he's in proximity of Fujishima. When around her, Watase immediately acts eager to please and is perfectly obedient. He seems to know full well that he will never win over Fujishima but claims that is what he likes most about her. These traits have caused Taichi to question if he is a masochist.
Watase has short, dark blue hair and teal eyes. Unlike most male students, he typically forgoes his uniform's sweater and tie. Many girls apparently admire Watase for his good looks and athleticism, but his only target remains Fujishima.
- Yaegashi Taichi: A male classmate. The two share a good friendship and Watase even trusts Taichi enough to be his wingman when trying to attract the attention of Fujishima, which Taichi considers a lost cause. Watase is shown to be somewhat jealous of Taichi's apparent popularity with girls and how close he is with Fujishima. By their third year, it is still unknown if Taichi ever came through with assisting Watase with Fujishima.
- Fujishima Maiko: His class representative and the object of Watase's affection. Greatly admiring her beauty and maturity, Watase is all but at her beck and call. Watase openly acknowledges that Fujishima is out of his league, which is what makes her all the more appealing to him. It seems that Watase liking Fujishima is related to one of Heartseed's phenomenons because in a world without those phenomenons, Watase would be going out with a girl from a different school. Watase teams up with Fujishima in the Couples Battle Royale in their third year. After the conclusion of the Couples Battle Royale, Watase confessed to Fujsihima and the two became a couple afterwards.
- Ishikawa Daiki: Watase's friend and classmate. Both being sports athletes, the two are shown to get along well. The two get into a minor argument when a phenomenon causes Nakayama to hug and kiss Watase, but they resolved this by talking it out and correctly blaming the phenomenon. As a result, they trust each other quite a bit.
- In the novel, he is described to have a wolf hairstyle.