Her best-known work was Kodomo no Omocha, also known as Kodocha, which was published in Ribon magazine, and won the Kodansha Manga Award for shōjo in 1998.
In 1999, she wrote a one-shot called Mizu no Yakata which focuses on the drama story that characters Sana and Naozumi of Kodomo no Omocha starred in.
In 2003, she worked on Pochi, which is about a junior high school girl who is stressed about life and her classmate whose mother treats him as a pet dog.
In 2004, Obana started a josei manga called Honey Bitter, about a girl who was mistreated by her ex-boyfriend but then has to deal with him as a coworker in their aunt's detective agency.
[6] In 2010, celebrating her 20th anniversary of her debut, she authored Deep Clear, a two-part crossover story with characters from Kodomo no Omocha and Honey Bitter.