In 2000, Onitsuka released her debut single "Shine" and gained recognition when its follow-up "Gekkou" became a hit.

Insomnia, her first studio album, released in the following year, topped the Japanese Oricon charts and has sold more than a million copies.

[1][2] She won the prize for lyrics of the 43rd Japan Record Awards in 2001 with "Memai", one of the singles from her debut album.

[9] By 2019 Onitsuka had released seven studio albums, twenty singles, five compilations, and several DVDs, selling at least 4.1 million units.

By the time she was ten, she wrote her first poems, receiving praise from her parents, friends, and teachers, who called them 'earnest efforts'.

It peaked at number six on the Oricon Weekly Singles chart and was certificated platinum by the Recording Industry Association of Japan (RIAJ).

As the lyrics of "Infection" can be interpreted as referring to the incident, EMI Music Japan cancelled further promotion to avoid causing controversy.

In November 2002, she made her comeback with the performance at the Nippon Budokan, the first show of her third concert tour "Chihiro Onitsuka Ultimate Crash '02".

[14] The album includes "Castle Imitation", the theme song for the PlayStation 2 role-playing game, Breath of Fire: Dragon Quarter.

In January 2003, the documentary television program, Artist Document Kami ga Maioriru Shunkan: Chihiro Onitsuka 22 sai no Sugao was broadcast on NHK.

To promote the single, she appeared several television variety shows, including "Mezamashi TV" and "Waratte Iitomo!".

On September 10, 2003, Onitsuka announced she would take a hiatus until the end of the year to undergo a surgery to remove polyps and recover from her poor throat condition.

In November 2003, she released "Watashi to Waltz o", which served as the theme song to the third season of Trick, as well as her previous hits "Gekkō" and "Ryūseigun".

It managed to sell approximately 3,000 copies and entered on the Oricon Weekly Albums chart at number one hundred and six.

In September 2004, she performed "King of Pain", "Smells Like Teen Spirit", and premiered her original song "Sodatsu Zassō" at Sweet Love Shower 2004.

The performance gained great public attention as she appeared in hard rock style costume, breaking down her previous pure image.

At one point she said that the reason of her departure from the music scene was because of mental fatigue caused by the series of new releases and tight schedules.

However, in an interview printed in the October 19, 2007, issue of the Japanese popular music magazine Barfout, Onitsuka said that in 2004 she had attempted suicide by overdosing on medication.

In addition, Onitsuka mentioned a polyp on her vocal cords around that time, as well as an eating disorder that saw her weight drop as low as 79 pounds (36 kilograms).

On July 26, 2005, a man who kept ringing the doorbell of Onitsuka's house for thirty minutes with a bouquet in his hands was arrested for housebreaking.

On April 26, 2008, she held her first solo show since "Unplugged '03" in 2003, entitled "Chihiro Onitsuka Concert Nine Dirts and Snow White Flickers" at Bunkamura Orchard Hall, Shibuya.

On September 26, 2008, she announced the cancellation of the scheduled "Chihiro Onitsuka Concert Tour 2008 'Vegas Code'" due to her poor physical condition.

Her single "Inori ga Kotoba ni Kawaru Koro" was released in May 2014 and served as the theme song to the Japanese supernatural horror film Ju-On: The Beginning of the End.

In September 2014, the debut album of Chihiro Onitsuka and Billy's Sandwiches Tricky Sisters Magic Burger was released.

In 2002, music critic Tetsu Misaki noted that Onitsuka was one of the few pop singers to sing about anger, citing lyrics such as isu o keritaoshi (椅子を蹴り倒し, "kick down the chairs") in "Shine" (2000) and fuhai shita sekai (腐敗した世界, "depraved world") in "Gekkō" (2000).

He praised her "strong spirit" and writing without hesitation, but felt like her lyrics were not like standard poetry, as they dealt with unpolished things.

Misaki further noted Onitsuka's use of body parts in her lyrics, especially legs, which is not common in Japanese popular music.

He pointed out "Gekkō" as being moonless, "Memai" not to do with dizziness and "Rasen" which, instead of having a spiral theme to the lyrics, seemed to talk about moving forward.