Tabuchi is a bit of a pain in the arse if she's going to waste time going to another classroom to yell at Oota, when she was going to go after the phone herself. What the hell, priorities.
Random thought: Imagine if these two grow up and get married. While they're "making a baby", Kashiwada remains expressionless the whole time, and Oota can't tell if he's doing a good job or not.