E – Everyone / A – All Ages
Like a G movie rating, the E – Everyone or A – All Ages rating means that the comic is suitable for readers from age 6 and up.
Y – Youth, Age 10+Similar to a PG movie rating, the Y – Youth, Age 10+ rating means that the title may contain mild violence and/or cursing. While these titles can sometimes be suitable for younger children, it's up to parents to know the maturity of their child.
T – Teens, Age 13+
The manga rating equivalent of a PG-13, T – Teen indicates that the comic's content may include some sexual innuendo and/or violent action scenes. Teen titles (just like Youth titles) should be carefully reviewed by parents to ensure that their child is mature enough for the material.
OT – Older Teens, Age 16+
OT – Older Teen rated manga may contain more explicit sexual situations and some violent scenes, including blood and gore. Manga is known for its graphic and violent tales, parents are encouraged to review these titles before giving them to teens. These are the equivalent of an "NC-17" or "R" rating.
M – Mature, Age 18+
Manga rated M – Mature" is strictly for adults. You can expect to find explicit sexual situations, strong language, and/or bloody battles and mayhem. This rating is equivalent to NC-17 or R. Parents are strongly advised not to give these titles to children due to their very graphic content.
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Manga and Anime follow different rating systems. Unfortunately, they are not always consistent across publishers. Sometimes, even though a rating may be there- it won't be easy to locate.
Most of the time(not always), stores will have mature rated books in shrink wrap to avoid minors from reading them- whereas the more PG manga will be less likely wrapped.
If you want to get an idea of what to pick and choose ahead of time, there are sites like animeplanet.com that you can use various filters and will also sometimes find (arguably) helpful reviews.
