My Past, Your Present, Our Future... (слэш)

*This work contains romaji; don't read if you don't like it!
As much as he’d been enjoying his retirement, the Rokudime couldn’t help but feel a little bored, a little lethargic as he went about his (predominantly) civilian life; sure, Naruto needed him from time to time and yes, he’d assisted Boruto with a few things and there was always Gai and Kurenai to visit.
However…
Overall, he’d just not expected to live this long; not that he wanted to die but having to live without a purpose was something he was struggling with until, quite out of the blue, a group of archaeologists ask for S-Rank level assistance and permits to explore what was once Uzushiogakure.
Being asked for by the head of the party (a woman he’d once saved), Kakashi accepts the assignment and promises his former student to keep him updated about his mother’s ancestral land and report back with any significant finds.
Unfortunately for him, he inadvertently triggers a seal in an ancient, half-destroyed fertility temple, a temple femmes and omegas had visited in order to find their fated mates.
Who could have known that such an accidental turn of events would result in him waking up in the past?