Flashback to a moment before the horrors and the mutations, back to when Mirai and Jason were, like, best friends! ... And before he started dating her sister!
Depicted here is Jason's inability to resist Mirai's big wet puppy dog eyes, pleading to hang out longer when they were supposed to part ways for the day. He made a valiant effort.
I'll be posting a an animatic version on my YouTube channel in a few days or so, so keep an eye out! 😁