What's the grade of Hideyoshi in the Mini Secret Service?

The Mini Secret Service is an animated film for children, with the mini secret service as the protagonist, telling the story of their struggle against evil forces in order to maintain justice and peace. In the play, Xiuzhi entered the sixth grade because of her young age. Xiuzhi is a member of the mini secret service team. Xiuzhi is a clever, brave and kind boy who is very good at inventing all kinds of magical props to help the mini secret service team complete their tasks.