Advice on taking leave for interviews

I work at a toxic place where wfh is not allowed and taking leave is extremely frowned upon.

I'm currently interviewing with a really promising firm (cleared four of the seven rounds of interview), which I have managed to get pass by taking 'long lunch breaks'

However, the remaining interviews occur during awkward timings because the interviewers are in a different timezone (can't use the long lunch break excuse) + there will be an upcoming case study which I probably will have to take leave for as well.

My issue here is that the remaining interviews will likely be staggered across the period of a month, which means that I have to apply for leave thrice during the next 3-4 weeks.

How do I navigate this situation without my boss getting suspicious, or worse, flat out denying my leave? Understand that my situation is rather unique, but my firm really is that toxic lol. Would really appreciate any good advice. 

(Already played the sick card twice this year, not a viable option)