Koyuki Hikawa — often called “Koyun” by fans — in The Ramparts of Ice is voiced by Anna Nagase in the Japanese version and Erika Harlacher in the English dub. Both actresses bring a quiet intensity to the role that suits Koyuki’s emotionally guarded nature, with Nagase’s youthful softness and Harlacher’s established range in reserved, introspective characters making them well-suited casting choices for the series’ central figure.
Anna Nagase (Japanese Voice Actor)
Date of Birth
March 31, 2005
About Anna
Anna Nagase (永瀬 アンナ) is a Japanese voice actress born in Tokyo, Japan, affiliated with the talent agency 81 Produce. Despite her young age, she has built a remarkably diverse portfolio across anime, video games, and other media since her career began. Her hobbies and special skills include reading, watching theater, and classical ballet — a background that speaks to the kind of disciplined, expressive artistry she brings to her performances.
Nagase first drew widespread attention with her role as Ushio Kofune in Summer Time Rendering, a performance praised for its emotional depth and naturalness. She has since demonstrated considerable range, voicing characters as tonally varied as the tragic Riko Amanai in Jujutsu Kaisen and the anarchic Harley Quinn in Suicide Squad ISEKAI. Her nomination for the Seiyu Award for Best Rookie Actor at the 17th Seiyu Awards (2023) confirmed her as one of the more promising voices of her generation.
As Koyuki Hikawa in The Ramparts of Ice, Nagase voices a socially withdrawn student who keeps an emotional wall between herself and others. The role calls for a performance that is understated yet quietly expressive — a balance Nagase has demonstrated across multiple roles in her young career. Her ability to convey interiority without overstatement makes her a natural fit for a character whose growth is measured in small, significant moments.
Hometown
Tokyo, Japan
Career Highlights
- Koyuki Hikawa – The Ramparts of Ice
- Ushio Kofune – Summer Time Rendering
- Riko Amanai – Jujutsu Kaisen
- Harley Quinn – Suicide Squad ISEKAI
- Rentt Faina – The Unwanted Undead Adventurer
- Naoki Azuma – Takopi’s Original Sin
- Akane Osaki – Akane-banashi
Full Current Filmography
The following list reflects documented credits and may not be exhaustive.
Anime (Selected, Chronological Highlights)
- Ushio Kofune – Summer Time Rendering
- Hack – Yurei Deco
- Mahoro Jin – Bucchigiri?! (Winter 2024)
- Youki – ‘Tis Time for “Torture,” Princess (Winter 2024)
- Rentt Faina – The Unwanted Undead Adventurer (Winter 2024)
- Harley Quinn – Suicide Squad ISEKAI (Summer 2024)
- Makina Kurusu – Milky☆Subway: The Galactic Limited Express (Summer 2025)
- Naoki Azuma – Takopi’s Original Sin (ONA, 2025)
- Riko Amanai – Jujutsu Kaisen: Hidden Inventory / Premature Death – The Movie (2025)
- Koyuki Hikawa – The Ramparts of Ice (Spring 2026)
- Akane Osaki – Akane-banashi (Spring 2026)
Video Games (Selected)
- Player – Code Vein II (2026)
Critical Reception
Anna Nagase’s casting as Koyuki Hikawa was announced as part of the main cast reveal for The Ramparts of Ice, with coverage noting her previous work on Summer Time Rendering as a key credential for the role. Her profile on MyAnimeList reflects growing fan recognition, with Koyuki Hikawa among her most favorited roles to date. Her broader body of work has earned her a reputation as a versatile young actress capable of anchoring emotionally grounded stories.
Social Media
Anna Nagase is active on X (formerly Twitter) at @anna_nagase.
Erika Harlacher (English Voice Actor)
Date of Birth
August 29, 1990
About Erika
Erika Lynn Harlacher is an American voice actress born and raised in California. She began her career as a production assistant at the post-production and dubbing studio Bang Zoom! Entertainment before transitioning into voice acting. Her early credits included roles in Hunter x Hunter (2011), Toradora!, and Kill la Kill, but her international profile rose significantly with the 2017 release of Atlus’ Persona 5, in which she voiced Ann Takamaki — a role she has since reprised across multiple spin-offs.
Harlacher has established herself as one of the more prominent voices in the North American anime dubbing industry, with a particular strength in characters who carry emotional weight beneath a composed exterior. Her performance as Violet in Violet Evergarden is widely considered one of her defining roles, showcasing her ability to portray restrained, quietly yearning characters with subtlety and care. This quality maps naturally onto Koyuki Hikawa, whose defining trait is the emotional wall she keeps between herself and the world around her.
The English dub of The Ramparts of Ice was produced by VSI Los Angeles, and Harlacher’s casting as Koyuki reflects the kind of considered matching of actor to character that the production appears to have pursued across its main cast. Her extensive experience in ensemble romantic and dramatic anime makes her well-positioned to anchor the series’ character-driven storytelling.
Hometown
California, USA
Career Highlights
- Koyuki Hikawa – The Ramparts of Ice
- Violet – Violet Evergarden
- Ann Takamaki – Persona 5
- Kurapika – Hunter x Hunter (2011)
- Yumeko Jabami – Kakegurui
- Shinobu Kocho – Demon Slayer: Kimetsu no Yaiba
- Elizabeth Liones – The Seven Deadly Sins
Full Current Filmography
The following list reflects documented credits and may not be exhaustive.
Anime (Voice Acting)
- Ami Kawashima – Toradora!
- Mimori Togo – Yuki Yuna is a Hero
- Princess Asseylum Vers Allusia – Aldnoah.Zero
- Kurapika – Hunter x Hunter (2011)
- Elizabeth Liones – The Seven Deadly Sins
- Yumeko Jabami – Kakegurui
- Violet – Violet Evergarden (2018)
- Crusch Karsten – Re:ZERO -Starting Life in Another World- (2018)
- Shinobu Kocho – Demon Slayer: Kimetsu no Yaiba (2019)
- Aya Arisugawa – TONIKAWA: Over the Moon for You OVA (2021)
- Iono – Pokémon Horizons: The Series
- Elizabeth Liones – The Seven Deadly Sins: Four Knights of the Apocalypse (2024)
- Asseylum Vers Allusia – Aldnoah.Zero -The Penultimate Truth- (2026)
- Koyuki Hikawa – The Ramparts of Ice (2026)
Critical Reception
Erika Harlacher’s casting as Koyuki Hikawa has been noted by fans familiar with her work in emotionally restrained roles. Her extensive track record in character-driven anime — particularly Violet Evergarden — has made her a well-regarded choice for a lead whose arc centers on emotional vulnerability and gradual openness. Her credits are documented across major databases including Behind the Voice Actors, where she ranks among the site’s more frequently credited English dub performers.
