She is 15 years old at the start of WataMote and her birthday is March 3rd which, according to Chapter 36, is a week after Tomoko's birthday. Given that she appears about a half-a-head taller than Tomoko, she appears to be 5'4".
She is the main character in the spin-off manga Watashi no Tomodachi ga Motenai no wa Dō Kangaete mo Omaera ga Warui, often shortened by fans to "TomoMote."
In middle school, Yū was Tomoko's best and possibly only friend. Initially a awkward looking girl, she enters high school with contact lenses, honey-dyed hair, and larger breasts much to Tomoko's jealously. Despite her radical makeover and having a boyfriend, Yū still regards Tomoko as her best friend. She is aware of the conflict between Tomoko and Kotomi but tries to bring them together.
Yū initially appears a naïve but very kind girl; however, she knows more than she lets on. In middle school, she had long black hair in a braid with glasses. On entering high school, she changed herself in many ways to fit in with her high school classmates, deciding that growing up and adjusting to society is better than falling behind. Still, she still enjoys hobbies like watching anime, and she still considers Tomoko her best friend. Tomoko frequently, in her mind, "sexually harasses" Yū through jokes such as word games only to discover Yū has more knowledge and actual experience. On Tomoko's 16th birthday, Yū asks her the definition of a lewd act, rendered as "XXX" in the manga, and after Tomoko gives the answer, "It's when a guy uses that to do that with that for that," Yū explains a "friend" said it to her. She then whispers into Tomoko's ear a number of things her "friend" has done which leaves Tomoko both suprised, satisfied, and concluding that she needs to grow up. In another infamous exchange, Yū slyly implies to Tomoko and Kotomi that she is no longer a virgin.
In more recent chapters, Yū demonstrates her insight into people. She initially appears oblivious to Tomoko and Kotomi's rivalry; however, it becomes clear as she forces them to enjoy time together that she simply politely ignored their conflicts. When in Chapter 124 Yuri Tamura meets her, shows jealousy of her friendship with Tomoko, and reacts by trying to embarrass Tomoko, Yū politely ignores Yuri's behavior. Instead, she seeks out Yuri before she can leave to get her Line account and implies she wants to talk with Yuri more. Yuri is left concluding that Yū is a kind person unlike Tomoko and her. For her part, Tomoko wonders if Yuri can handle a girl who already adds "chan" to the end of her name.
Yū's appearance changed between middle school and high school. Her middle school appearance is depicted in the manga in a number of flashbacks, the first of which occurs in Chapter 3, TomoMote, and WataMote Episode 13. She had long, black hair tied in braids that sometimes reached all the way to her ankles with straight bangs. She wore square glasses. She also wore a sailor fuku outfit with a long skirt that reached her knees. According to Tomoko, both she and Yū had the same in chest size in middle school. When Tomoko first meets Yū again in Chapter 3, she is stunned that Yū has shorter, bleached hair, wears contacts, changed her clothing style, and developed significantly more than she has. Yū now wears a school uniform that consists of a white collared shirt with a green bow, a short dark-brown skirt, and black thigh-high socks. The socks allow her to wear the shorter skirt, and Tomoko wonders if Yū is trying to "seduce" her by wearing a mini skirt. Tomoko also noted her new appearance as "slutty-looking," in English as a translation for the Japanese for "bitch" which as a different connotation than in English and means a popular and sexually active girl.
- Volume 01: Chapters 3, 8,
- Volume 02: Chapters 12, 14
- Volume 03: Chapters 20, 21, 24,
- Volume 04: Chapters 29, 30, 31, 33, 36,
- Volume 05: Chapters 37, 46
- Volume 06: Chapters 47, 51, 54, Special, Omake
- Volume 07: Chapters 56, 57,
62, 64, 65, Omake
- Volume 08: Chapters
70, 71, 77
- Volume 09: Chapters 78, 83, 84, Special
- Volume 10: Chapters 93, Special
- Volume 11: Chapters 100, Special
- Volume 12: Chapters 110,
112, 113, 120, 121,
- Volume 13: Chapters 124,
- Volume 14: Chapters
133, 136, 137, 138, 140
- Volume 15: Chapter 143, 151
- Volume 01: Chapters 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28
Strikethrough episodes or chapters indicate the character was mentioned but did not make a physical appearance)
Tomoko and Yū have been best friends since middle school. They parted ways after graduation and now attend different high schools. Tomoko implies that Yū was never a good student, and in a flashback, describes Yū's stunned look at the end of the her high school entrance exam, with typical Tomoko tact, as if she had "been raped." They still remain close and make time to meet up occasionally. Unbeknown to Yū, Tomoko harbors some jealousy toward her because of how much she has matured since middle school, appearing to have more friends and even a boyfriend.
Kotomi has known Yū since middle school. Yū treasures her relationship with Kotomi and was pleased to see her after they graduated middle school. Kotomi likes to hang out with Yū and decides to tolerate Tomoko's presence because of it. Yū tries to prod Kotomi and Tomoko together.
- She and Tomoko both enjoy anime and manga.
- Chapter 100 hints that she lost her virginity during her second year of high school.
- In Volume 11 Special Edition, in response to the challenge by Tomoko to buy a useless gift for Christmas in an outing with her, Tomoko, and Kotomi, she buys a pack of condoms.
- According to Chapter 15 in TomoMote, Yū had a pet cat before this chapter.
- The name of her and Uchi's hairstyle is a "bobcut" (ボブカット・bobukatto)."
- As depicted in Chapter 143, Yū is left handed.
- "Lucky, I wish I could've gone to the same high school as you, then we could've got to seen each other everyday..." - to Tomoko.
- "Yū was my old friend in middle school. She had rather average looks and rather average grades. She entered a rather mediocre high school." - Tomoko recalling Yū in middle school.
|Female Characters||Tomoko Kuroki | Shiki Futaki | Anna Haruna | Shizuku Hirasawa | Akari Iguchi | Hikari Itō | Megumi Imae | Asuka Katō | Kayo | Kotomi Komiyama | Mrs. Kuroki | Koharu Minami | Miyazaki | Nagi | Miho Narita | Yū Naruse | Hina Nemoto | Ogino | Akane Okada | Reina | Fūka Sasaki | Kiko Satozaki | Sayaka | Yuri Tamura | Mako Tanaka | Emiri Uchi | Masaki Yoshida|
|Male Characters||Tomoki Kuroki | Aomatsu | Art Teacher | Hatsushiba | Homeroom Teacher | Jun Ishimine | Kakinuma | Yoshinori Kiyota | Kosaka | Mr. Kuroki | Suzuki | Nico Tanigawa | Wada | Yocchan|
|Minor and Unnamed||Minor and Unnamed Recurring Characters|
|Manga Volumes||1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18|
|Anime Episodes||1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | OVA|