Deep Forest

There is a large virtual space called "Deep Forest," where many people go as avatars. Origa is a schoolgirl who has become an explorer in Deep Forest in an effort to discover the reason behind her mother's death. Luckily, she has a famous hacker as a partner and guide, a monkey avatar called Jr. Deep Forest is a dangerous place, contested by the company she believes is responsible for her mother's death, hackers, and others. Origa has a difficult path to travel in order to uncover the truth.

(Source: MangaHelpers)