Yankumi meets Kuma’s mom in the bar. But, during that time, she didn’t know yet she’s Kuma’s mom. She only found out when she saw her in the school grounds. She informed her not to mention anything about it in school so as not to cause trouble to her job.
There’s nothing exceptional in this episode. We just get to see more of Kuma and his friends’ thickheadedness (Is there such word?). I’m glad they decided to attend math tutorial even though it’s for other reasons and not because of their low scores.