I feel like chapter 5 is missing some pages.

I didn't get that feeling, what part is off?

Sister starts running away and then all of a sudden, here uke is behind her. There also looks like a part where another baddie came and then uke is own the ground as if he got hit but we didn't see the hit.

I thought so too!

He totally gets hit on page 20. There is a "whack" sound and then he falls down while we see a guy behind him with an iron bar.
The part about the girl running I think is just not very well explained, it can happen in action scenes, specially when they try to surprise us. Sometimes it is so clear in the creator's mind that they forget that the reader needs a bit more of information.
That's what I think.