When they separated, ml basically returned to his original timeline (4 years before the timeline of the mc). Knowing the mc would leave his province at X date 4 years later, he simply waited for 4 years to pass and went to the area mc is at in the present day. For ml, 4 years has passed since they separated, but for the mc, it was only a couple of minutes.
Just a quick question. Did Shun time traveled to pass those 4 years or did he actually wait for 4 years? Meaning if he did wait for 4 years, Shun (2018 ver) stayed in his timeline and simply met with Yuudai in 2022 at some place. Whereas if he time traveled 4 years, meaning a day of Yuudai timeline is equivalent to a year of time traveling of Shun. I don’t know if I messed that up, but please correct me if I did in my explanation TwT !

Anyone pls fill me in how he manage to come to 4 years later? I dont understand