The popular Anime-Manga-Japan---etc news related site AnimeNewsNetwork, have and opening position for a Manga Reviewer in his staff.
As published in its Website
"Anime News Network presently has an opening on the editorial staff for a freelance manga reviewer. We are searching for an experienced writer who is intimately familiar with and passionate about manga, someone who is open-minded enough to embrace everything the medium has to offer and provide a strong point of view and thoughtful analysis.
This position is paid on a per-article basis. Reviewers are expected to turn in a minimum of 5 reviews a month. Review material will be provided. Further details on the position will be given to qualified applicants.
Applications must include a cover letter and at least 2 writing samples, preferably previously written manga reviews, each being over 400 words. Blog links are acceptable but must link directly to the sample. Applications must be sent to firstname.lastname@example.org, and the subject must read "Manga Reviewer Application " or it will be discarded.
Unfortunately it will not be possible for Anime News Network to respond to every submission, therefore we will only respond to candidates that we are considering."
There is not a deadline for the applications to be submited, instead of, in the words of one of ANN executives "When the listing is taken down, the position has been filled. There's no deadline but if you're interested you should apply ASAP. I already have a small mountain of applications. " Zac
Manga Reviewer discussion thread