Yōko Hikasa is a prominent Japanese voice actress and singer born on July 16, 1985, in Kanagawa Prefecture, Japan. Her interest in acting was sparked during childhood by the anime Sailor Moon and Neon Evangelion, particularly admiring the range of voice actress Kotono Mitsuishi. To pursue this career, she enrolled in the Nihon Narration Engi Kenkyūjo voice actor training school after high school.

Hikasa made her debut as a voice actress in 2007 with a role in the anime Sketchbook: Full Color's. Her career gained significant momentum in 2009 when she was cast as Mio Akiyama in the immensely popular series K-On!. This role became a landmark in her career, and as part of the in-series band "Ho-kago Tea Time," she learned to play the bass guitar left-handed to match her character, despite being right-handed. In 2010, she and her K-On! co-stars received the Singing Award at the 4th Seiyu Awards for their musical performances as the unit.

Following her breakthrough, Hikasa established herself as a leading voice actress in the industry, taking on a wide array of iconic roles. She is well-known for voicing strong-willed and memorable characters such as Rias Gremory in the High School DxD series, Kyoko Kirigiri in the Danganronpa franchise, Emi Yusa in The Devil Is a Part-Timer!, and Stephanie Dola in No Game No Life. Her filmography is exceptionally diverse, encompassing roles like the determined Houki Shinonono in Infinite Stratos, the elegant Diana Cavendish in Little Witch Academia, the goddess Freya in the Is It Wrong to Try to Pick Up Girls in a Dungeon? series, and the serious Tomoe Udagawa in the BanG Dream! multimedia franchise. She has also taken on leading roles in newer series, such as the 2021 remake of Shaman King as the protagonist Yoh Asakura and as Utahime Iori in Jujutsu Kaisen. In 2025, she was awarded the Best Supporting Actress award at the 19th Seiyu Awards.

In addition to her voice acting, Hikasa has a successful career as a singer. She made her solo debut in 2013, performing the first ending theme song "Utsukushiki Zankoku na Sekai" for the hit anime Attack on Titan. She has continued to release music under the Pony Canyon label. She was also part of the voice actress unit Ro-Kyu-Bu!, formed with Kana Hanazawa, Yuka Iguchi, Rina Hidaka, and Yui Ogura for the anime Ro-Kyu-Bu!, for which they performed the opening theme.

Beyond her professional work, Hikasa is known for creating the popular Japanese buzzword and pose "Tehepero (・ω<)," which she often used on radio shows and blogs to lightly apologize for a mistake in a cute way. The phrase gained widespread popularity, winning awards and being used by other celebrities. Her personal hobbies include cooking, for which she holds certifications as a food instructor and natural food coordinator, as well as sewing, calligraphy, and playing softball.

After being affiliated with the agency I'm Enterprise for many years, Hikasa announced her departure on January 20, 2023, to work as a freelancer. She later founded her own voice actor agency, i.nari Co., Ltd., in September 2024, becoming its president and a affiliated artist. She has been married since 2015.