A manga booklet given out to Japanese movie attendees for Sonic the Hedgehog 3.

Back on Sonic's home planet, Eggman has collected all 7 of the Chaos Emeralds, and is about to have absolute power when Sonic interferes, causing an explosion that sends everyone from their world to Earth. Sonic and his friends team up with 12 year old Christopher Thorndyke to collect all the Chaos Emeralds and defeat the evil Dr. Eggman. 
(Source: Anime News Network)

Short comics released on the official Japanese Sonic the Hedgehog website, Sonic Channel, as part of the franchise's 25th anniversary celebrations. Each comic focuses on individual Sonic characters featured in the Character Profiles on Sonic Channel often featuring slice-of-life moments or references to their backstory in past games. (Source: Sonic Wikia, edited)

Collection of several short stories, including omake (extra) koma stories, published as an anthology. The stories are often very slapstick. 
(Source: Wikipedia)

Manga series focused on Shadow The Hedgehog in order to promote Sonic X Shadow Generations. 
Shadow and Maria live on the Space Colony ARK, but one day they are suddenly attacked by the Earth Defense Forces who are “disposing of dangerous biological experiments”. Shadow and Maria try to protect each other, but Maria is hit by a merciless bullet…? 
(Source: Shogakukan)

Original manga based on the Sonic the Hedgehog video game franchise
 
The story follows Sonic and a boy named Yuuta embarking on a great adventure together.

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