Ranma had a son Ryuu with Akane and then got locked as a girl so she left. Ryuu dislikes Ryoga, his step father and wants to meet his real dad. He and his half siblings are suspended for fighting and their parents have gone missing so they have to go to live with Ranma despite her shame. Ranma picks up her other daughter Ryoko who is a mad scientist and sends the other kids to school where they interact with kids from the rest of the Nerima crew.