Senku finally meets someone who thinks like him, and the show becomes a completely different animal, two geniuses playing 4D chess while the world burns around them. The hard science takes a backseat to pure intellectual warfare, and that trade feels earned because watching Xeno dismantle Senku's plans is genuinely tense in ways the earlier seasons never were. A spaceship race to the moon against a rival who wants the exact same thing for completely different reasons turns the whole series into a sprint where every move matters.

Senkuu and the Kingdom of Science have come through the fight on Treasure Island, and with the petrification device they captured, they bring Tsukasa back to life and he joins their side. Their next target is Why Man, the mind behind humanity's petrification, whose base is on the Moon. Getting there means building a spaceship from nothing, which calls for huge manpower and resources spread around the globe. The team sets out on the ship Perseus, first bound for America to find corn for the Revival Fluid. There they meet opponents whose science matches or beats their own. The first cour of the fourth season mixes action, adventure, comedy and sci-fi.