For context this is the what she says right before this line:
I'm having trouble with analyzing the sentence. It is clear to me that she is basically saying "Shall I go swimming?" in some self-directed rhetorical question but what I can't figure out is the nuance of using こよう(or its contracted form here with かな, こよっかな).
From what I read on Tofugo about using 来る with て-form and from the discussion on Wanikani's forums I get two different explanations (I'm using parenthesis for emphasizing the nuance in Japanese that is mostly lost when translated into natural English):
- てくる with a movement verb means that something is coming your way. That would mean that swimming is coming Takagi's way? As in "Shall I go (have some) swimming (in my way/direction)" Seems a little weird.
- The use of てくる here is like that of 行ってくる so the nuance would be that she saying "Let's go (out) swimming (and come back later)" which makes more sense since this is a class so she'll swim and then she'll go to the next class\recreation\lunch\whatever is next on her agenda for that day however it still feels weird.
While it is possible that two different nuances exist for using てくる, which the native speaker will tell apart through context, I find both explanations somewhat unsatisfying. I'd appreciate it if someone could verify what is the nuance of using てくる here and in general if both sources are right or if one of them is wrong.