The first 3 pages of ch 57 is 5 years after the USA trip. And then it goes immediately back into a flashback 5 years into the past (which would be right after the USA trip of ch 56). So you can ignore the first three pages if you think it's confusing and ignore the fact that a 5-year time skip is coming. Then the rest of ch 57 would be stuff that happens right after Yuki and Itsuomi come back from their trip in ch 56
For anyone that's confused:
The first 3 pages of ch 57 is 5 years after the USA trip. And then it goes immediately back into a flashback 5 years into the past (which would be right after the USA trip of ch 56). So you can ignore the first three pages if you think it's confusing and ignore the fact that a 5-year time skip is coming. Then the rest of ch 57 would be stuff that happens right after Yuki and Itsuomi come back from their trip in ch 56