Tomoko Maruo, now known professionally as Chiko, is a Japanese voice actress and narrator born on June 22, 1966, in Yokohama, Kanagawa Prefecture. She is a graduate of the Aoni Juku Tokyo School, having completed its 6th term, and is affiliated with the talent agency Aoni Production. She began using the stage name Chiko professionally in December 2012.

Maruo's career has been active since the late 1980s, with a significant body of work in anime, particularly in original video animations and television series from that era. Her voice is frequently used to portray young boys and adolescent characters. In addition to animation, she has also provided narration for numerous documentaries, dramas, and commercials.

Her filmography includes a wide variety of roles. In television anime, she is known for voicing A-tarou in Mōretsu Atarō, Yuuma in Shōnen Ashibe and its sequel Shōnen Ashibe 2, Kenta in Kariage-kun, and Saladin in Super Bikkuriman. She also voiced the character Jintei Peter in the original Bikkuriman and its related work, Bikkuriman: Moen Zone no Himitsu. Other notable TV roles include Fire and Rami in Transformers: Victory, and Buutan in Tonde Būrin.

Maruo also contributed her voice to many prominent OVA and film projects. Her OVA roles include Chay in Mobile Suit Gundam 0080: War in the Pocket, Apoline in Shamanic Princess, Nami in Ariel and Yuki Nishijima in Ariel Deluxe, and Mogu in Harbor Light Story - Fashion Lala yori. In animated films, she voiced Ohana in Rail of the Star - A True Story of Children and War, Zangya in Dragon Ball Z: Bojack Unbound, Anna in Mobile Suit Gundam: Char's Counterattack, and a young Fiore in the Sailor Moon R movie.

Throughout her career, she has had recurring collaborations with fellow voice actors such as Kōichi Yamadera and Tōru Furuya, and frequently appeared in productions with other Aoni-affiliated talents. In 1986, early in her career, she was a member of the voice actor unit QP's, which released a single.