Eggman shows up to steal Tails' Chaos Emerald. Sonic is then convinced to come to Tails' Workshop in Mystic Ruins to see a project of his. The two later have a small conversation in Station Square where Tails tells Sonic that he was using the plane to test the power of a Chaos Emerald he had found. Hurrying to Emerald Coast, Sonic finds Tails. The next day, Sonic is relaxing by a pool in Station Square until he sees Tails crash on the beach in his newest biplane. Eggman has been observing Sonic's clash with Chaos, confident in Chaos's supremacy despite its defeat. As the police retreats, Sonic steps in and defeats Chaos, but it escapes through a water drain. Following them, he sees the police surround Chaos, only to notice upon opening fire at it that their weapons are useless against Chaos. In Station Square, Sonic is jumping across rooftops, enjoying himself, until he notices the Station Square Police Department staff rush to City Hall.

Sonic arriving to face off against Chaos after Station Square's police force retreats. When Sonic the Hedgehog learns of Eggman's plans, he and his friends spring in to action to stop Eggman and they start another journey for the Chaos Emeralds. Eggman's goal is to control Chaos, and use its destructive powers to collect the Chaos Emeralds and conquer the city and turn it into 'Robotnikland'.' To help him, he has created the E-100 Series robots. Because he believed it to be true, he seeks out the Master Emerald and shatters it, freeing Chaos in the process. Eggman learns of the legend surrounding Chaos. This enraged Chaos, who transformed into Perfect Chaos and destroyed all of the echidnas, except for Tikal, who sealed herself away in the Master Emerald with Chaos, and the magic caused the area surrounding the shrine to become Angel Island, also known as the continent in the sky. Although Tikal and the Chao stood against him, he ordered his soldiers to charge anyway, resulting in many Chao being injured. When Pachacamac sought to expand his clan's territory, he wanted to steal the Chaos Emeralds and use their power to defeat his rivals. A peaceful echidna named Tikal, daughter of Chief Pachacamac, befriended the Chao that lived at the altar and their protector, the water god Chaos. Three thousand years ago, the Chaos and Master Emeralds were kept at an altar near the territory of a clan of echidnas (the Knuckles Clan).

Spoiler warning: Plot, ending details or any kind of information follow.

10.4.1 Christmas Trees in Station Square.

Sonic adventure 2 upgrade locations