From Sonic Retro
English story from US manual
One day, while wandering around, Sonic caught a glimpse of something on Emerald Beach. What he saw upon reaching the Beach was a battered robot. Although he tried to communicate with it, there was barely a response.
Then he hit upon the idea; "I know who can fix this robot - Tails!" However, soon after, Shadow appeared wanting the robot.
"So You already have it. Give me the robot, Sonic" said Shadow.
"What if I say no?" Sonic responded.
It seems another storm is starting to brew...