Sonic Underground: The Ongoing Search

Sonic Underground: The Ongoing Search is a 2023 American-Japanese anime TV series that serves as the continuation of the DiC Entertainment TV series Sonic Underground and is based on the video game franchise Sonic The Hedgehog by Sega. The series follows Sonic, Sonia and Manic as they continue their quest to find their mother Queen Aleena while fighting the evil Dr. Robotnik and his minions along the way.

Plot
The anime picks up where the original show left off. After causing the collision in the episode Virtual Danger, Sonic, Sonia and Manic continue to search for their mother Queen Aleena and first decide to check out Shooting Star City, where they meet a human teenager named Ethan Dawson, who quickly befriends them and becomes their companion. The first half involves the four fighting Dr. Robotnik and his henchmen Sleet and Dingo with the Hedgehogs performing songs throughout and the four making new friends along the way. The second half starts with Sleet and Dingo turning against Robotnik and becoming Freedom Fighters for the rest of the series.

The newly extended group travels in a new van which resembles the TARDIS from the British science fiction series Doctor Who. The Doctor himself is featured as one of the main characters in this half. Eventually, the group reaches Dr Robotnik's new lair and prepares to destroy it with him inside. However, Sleet, Dingo and the three hedgehogs are captured and brought before the evil doctor. Sonic, however, is happy to see Aleena, only to find that she has been brainwashed into serving Robotnik, much to his and Manic's shock and Sonia's sadness. Robotnik reveals that Aleena refused to marry him, as she was already married to the King, so he took over Mobius in hopes of punishing her for this. He then has the three hedgehogs placed inside glass spheres and starts up a machine that will slowly have them knocked out by the electricity the machine contains so that he will be able to roboticize the hedgehogs. However, Ethan, the Doctor and the music group Plave, who became companions for the Sonic Underground during the first half of the series, arrive and Ethan manages to free Aleena from the brainwashing by revealing himself as Takashi Komuro from the manga series Highschool of the Dead and telling her that his discovery of Robotnik being behind the zombie apocalypse that took place in his dimension caused him to begin hunting down Robotnik in order to destroy him, the reason why he came to Mobius in the first place, while Sleet and Dingo, after being freed from their cell by the other six, shut down the machine, destroy it and the roboticizer and free the hedgehogs, causing them to reunite with Aleena. Although the Royal family is reunited, Robotnik shows up in a large robot controlled by him but before he can wipe out the group and the entire Resistance, Sleet and Dingo sacrifice themselves by fending him off and getting transformed into magic essences and as a result, the three hedgehogs and Takashi become very powerful and manage to destroy the robot in a matter of seconds with him in it, creating a blast that restores all life on Mobius, destroys Robotnik's lair, changes Robotropolis back into Mobotropolis, turns all the Robians back into Mobians, transforms all the zombies in Takashi's dimension back into humans and causes every zombie that was killed by Takashi to come back to life as humans.

With his quest complete, the Royal family reunited and Robotnik's tyranny at an end, the group bids each other a friendly farewell before they part ways with Takashi returning to his dimension, Plave returning to their world as well and the Doctor summoning his TARDIS and departing back to his own dimension. Manic is eventually crowned the new King of Mobius. However, Robotnik has survived the blast and decides to try a new plan with something different. One year later, having found out about Robotnik's survival, Sonic says goodbye to his siblings and Aleena and heads off to stop Robotnik's plans, leading for the entire video game series to begin.

Episodes

 * 1) Dangerous Wish: Sonic, Sonia and Manic travel to a place called Shooting Star City which is entirely populated by humans and they meet a 15-year-old teenage boy who has come to Mobius for a reason. But a deadly wish made by a surviving Robotnik puts the city in danger and the hedgehogs and their new friend must work together to put an end to this awful wish.