I am a US citizen with a US passport who enters Japan with 90 day temporary visitor waiver. I usually stay around 85-87 days per 90 day temporary visitor waiver. I have a lot of savings, don't work in Japan, and mainly go to see the country and visit my girlfriend, so I don't do anything illegal.
I've been to Japan 4 times:
Year #1 1st: October 26 2017-January 20, 2018 (A couple days under 90 days)
2nd: April 2, 2018-June 28, 2018 (A couple days under 90 days Total: Around 175 days
Year #2 3rd: October 26 2018-January 20, 2019 (A couple days under 90 days)
4th: March 10 2019 - June 6, 2019 (A couple days under 90 days) Total: Around 175 days
Note: Immigration never said anything to me despite me staying almost the full 90 days per visit these 4 times.
I left Japan June 6 2019 to go to my home in USA for 1 month exactly and will return to Japan in 10 days July 7 2019. I am worried of being denied entry and not given another 90 day temporary visitor visa waiver when I return because within the last year I already stayed 175 days and the year would "reset" on October 26, 2019.
I heard that the 180 day limit is not an official rule but I'm not sure how strictly it is enforced.
Is it likely I'll be denied by immigration or questioned? What information/documents should I bring to improve my chances of being permitted? Would an invitation letter from my girlfriend help at all?
I'm really concerned about being on a flight from USA to Tokyo (around 20 hours) only to be denied.