Big Bug (S01E05)
The day begins with two girls chatting about Ulrich when Sissi interrupts, claiming that Ulrich is secretly in love with her. Later, Odd and Ulrich decide to prank Sissi by sending her a text about "true love." Meanwhile, the town is facing chaos due to a mysterious virus, and two trains are on a collision path, one carrying dangerous toxic chemicals that threaten the town's safety. Yumi, unable to reach Ulrich and Odd because they've turned off their phones, searches for them. During the prank setup, Sissi accidentally opens a shed and is startled by Kiwi, Odd's dog. This leads to Odd getting in trouble for bringing Kiwi to school. Yumi eventually finds Ulrich and Odd, but Odd is stopped by Jim and taken to the principal's office. To assist Aelita in fixing Xana, they need everyone on board—where could Odd possibly be?