The Ramparts of Ice (Japanese: 氷の城壁, Hepburn: Kōri no Jōheki) is a Japanese web manga series written and illustrated by Kōcha Agasawa. It was first published as a webtoon under the Line Manga Indies section, and after collaborating with the Margaret editorial team, it was picked up for official serialization through the Line Manga digital service from January 2020 to April 2022. Shueisha published its chapters in 14 tankōbon volumes from July 2023 to February 2025.
The series follows Koyuki Hikawa, an introverted high schooler who keeps her distance from others, until three of her schoolmates draw her out and help her enjoy her adolescence to the fullest.
An anime television series adaptation produced by Studio Kai aired from April to July 2026. A second season is set to premiere in October of the same year.
Contents
Synopsis
High school student Koyuki Hikawa has trouble interacting with others, instead preferring to keep her distance and spend her time alone. However, when she meets Minato Amamiya, he suddenly starts trying to close the distance between them.
Characters
Main characters
Koyuki Hikawa (氷川 小雪, Hikawa Koyuki)
Voiced by: Anna Nagase (Japanese); Erika Harlacher (English)
A heavily introverted high school girl. Due to prickly encounters and teasing from boys (on account of her diminutive stature) while growing up, Koyuki keeps her distance from most people except Miki and keeps up a cold exterior represented visually as ice palace walls, which causes her to be dubbed "The Ice Queen" by her fellow students. However, she slowly loosens up over time after becoming more open with her friendship with Miki and getting to know Yota and Minato. Because of her trauma and limited social interaction, Koyuki overthinks every single thing she says, creating awkward moments. Initially, she does not like Minato at all, as his extroverted and invasive personality scares her. However, she eventually warms up and develops feelings for him. She is left heartbroken when Minato begins briefly dating Momoka Kuriki, a manipulative student who emotionally abuses her the same way she had been abused back in middle school. However, just as she begins to believe she should let go of Minato for good, he finally returns to her and confesses his true feelings, to which she reciprocates.
Miki Azumi (安曇 美姫, Azumi Miki)
Voiced by: Fūka Izumi (Japanese); Brianna Knickerbocker (English)
Koyuki's childhood best friend whom she has known since elementary school. She has a compulsive need to please people and look good in front of them, which causes her to hide her rowdier, more casual self with a friendly, picturesque exterior. As a result, she has become the class idol, a label she holds displeasure with. This causes her to limit her interactions with Koyuki inside school until the latter befriends the boys. Miki is initially wary of Minato's reputation as an insincere player in relationships, and fears his pushy behavior will end up hurting Koyuki further. However, as Minato learns from his mistakes and warms up to them, she begins to appreciate him more. Initially, she was oblivious to Yota's crush on her, and rejected him when she felt unsure about her own feelings. But with time, seeing how he continued to be close to her despite her rejection, she realizes she is in love with him too, and finally returns his feelings.
Supporting characters
Tsubasa Igarashi (五十嵐 翼, Igarashi Tsubasa)
Voiced by: Chiaki Kobayashi (Japanese); Ryan Colt Levy (English)
A soccer team member who was classmates with Koyuki and Miki in middle school. Due to the bullying and trauma she experienced in her past, and how other girls constantly accused her of having a crush on him, despite her vehement denials, Koyuki has become afraid of him.
Tsukiko Shimojima (霜島月子, Shimojima Tsukiko)
Voiced by: Sakura Shinfuku (Japanese); Kayli Mills (English)
Koyuki's classmate and a member of the art club.
Momoka Kuriki (栗木桃香, Kuriki Momoka)
Voiced by: Akari Kitō (Japanese); Laura Stahl (English)
An antagonistic student that joins Koyuki's high school. She hides her true malicious and manipulative self under a friendly and bubbly person, as she pretends to befriend others around her. She is in love with Minato, which leads to her fully resenting Koyuki with a passion, as Minato's obvious crush on Koyuki enrages her. Her crush on Minato slowly turns into an obsession later on when he starts briefly dating her, and her bullying and abusive behavior towards Koyuki only escalates further. His lack of feelings for her, however, weighs on her the longer the relationship lasts, and after they break up, she vows to improve herself and not make the same mistakes she made with him.
Yūki Azumi (安曇優希, Azumi Yūki)
Voiced by: Kakeru Hatano (Japanese); Caleb Yen (English)
Miki’s mischievous younger brother, who is in the same grade as Momoka and Akine. He is also on good terms with Koyuki.
Media
Manga
Written and illustrated by Kōcha Agasawa, The Ramparts of Ice began publication as a self-published webtoon under the Line Manga Indies section for about two years, before the author was contacted by the Margaret editorial department, who facilitated its official serialization through Line's Line Manga digital service, being published from January 10, 2020, to April 28, 2022. Shueisha published the manga in print, under its Jump Comics imprint, with 14 tankōbon volumes released from July 4, 2023, to February 4, 2025.
The series is published in English on NTT Solmare's MangaPlaza website.
Anime
In January 2025, it was announced that the manga would receive an anime television series adaptation. It is produced by Studio Kai and directed by Mankyū, with series composition by Yasuhiro Nakanishi, characters designed by Miki Ogino, and music composed by Kanade Sakuma and Natsumi Tabuchi. The series aired from April 2 to July 2, 2026, on TBS and its affiliates. The opening theme song is "Tōmei" (透明; 'Invisible'), performed by Novelbright, while the ending theme song is "Sakasama" (逆様; 'Upside Down'), performed by Polkadot Stingray. Netflix is streaming the series globally.
Following the airing of the first season's finale, a second season was announced, and is set to premiere on October 1 of the same year. The opening theme song is "Escort" (エスコート), performed by The Beat Garden, while the ending theme song is "Hanakage" (花蔭), performed by Superfly.
Reception
Before its serialization, The Ramparts of Ice received a special prize at the "Shueisha Shōjo Manga Grand Prix Powered by Line Manga Indies 2018 Summer". It ranked nineteenth in the web category at the seventh Next Manga Awards in 2021. It ranked first in the Comic CMoa Annual Ranking's josei manga category in 2022. It ranked second in AnimeJapan's sixth "Most Wanted Anime Adaptation" poll in 2023. It was nominated for the 69th Shogakukan Manga Award in 2023. It ranked fifteenth, along with The JoJoLands, on Takarajimasha's Kono Manga ga Sugoi! list of best manga of 2024 for male readers. It was ranked sixth in the Nationwide Bookstore Employees Recommended Comics of 2024 list. The series won the 2024 Vertical Manga Award in the completed comic category.