I realized that I haven't reviewed any shonen manga on my blog yet! Shonen manga are geared towards boys and feature more action and adventure with a strong focus on friends and rivals. Some popular shonen series are Bleach, One Piece, and Naruto.
Blue Exorcist by Kazue Katō is an exciting series that is fairly new. We began to see it in the US with the release of the anime in Japan, but the manga began in 2009 in Japan.
Two twin brothers are raised by Father Shiro Fujimoto. Rin Okumura is the protagonist-- he is reckless and always in trouble. Father Fujimoto ends up dying trying to protect him, which is when Rin discovers that he is the son of Satan. In trying to exact revenge he draws the Kurikara sword, which unleashes his demonic powers. When he meets Mephisto Pheles at Father Fujimoto's funeral he declares that he wants to become an exorcist like Father Fujimoto was, and Mephisto Pheles happens to be the headmaster at the True Cross Academy where young exorcists go to train.
Upon arriving at True Cross Academy Rin learns that his brother Yukio is not only already at True Cross Academy, but he is an instructor at the academy! Rin must conceal his nature and learn to control his powers. He wants to fit in and make friends, but he's also living in his brother's shadow.
Throughout the series we see Rin grow as a person, as well as discover the story behind Father Fujimoto, True Cross Academy, and the history of exorcists. Blue Exorcist is a shonen manga, so it focuses on action-- training, fighting-- and it's fast-paced. Although Rin is the main character each character is interesting-- there are very few that lack a background and purposeful role.
As far as shonen manga goes this has a stronger plot. The cast of characters is smaller and I think that allows deeper reflection on the characters and their goals and relationships than other series tend to do. Even the "bad guys" are complex and well-written instead of random enemy #5497 that you forget about in a few volumes. Right now the series in the US is at volume 8, but only up to volume 9 in Japan!
I recommend checking out Blue Exorcist now before it's a million volumes long (shonen manga series tend to be very lengthy... Bleach is at volume 56 right now, and that's not one of the longest).