A young girl finds herself always falling in love with the the type of guy who gets trucked. It's a whirlwind of emotions the first time truck-kun takes someone from her and she is devastated when the boy who helped her through her grief over her first boyfriend gets mowed down too but by the fifth one, she realizes that it's always the same truck that gets the boys and girl she dated. 

Tracking the thing becomes an obsession as she realizes that she's not the only one who's suffered at Truck-kun's hands from the scant few photos and videos she finds online that prove her suspicions to be true. She forms a group dedicated to finding this serial killer and one day she gets a private message from someone who tells her that they can shed a light on the mystery.

It turns out to be a rare returnee from an isekai world who came out from it pissed at the suffering he's had to go through. He's managed to retain a smidgen of his powers from his travels and he wants her help to make Truck-kun pay. Thus begins a bloodbath that pits men against a supernatural balancer of worlds all in the name of revenge.

>FeMC keeps attracting isekai protag types because she's a damsel princess type
>Truck-kun is actually truck-chan and the truck is a magitek golem
>Truck-chan is also the returnee's girlfriend but she deliberately got into a relationship with him because it was hard to set up the right conditions to isekai him
>Truck-chan puts up a struggle and isekais FeMC's group one by one but she personally puts herself at risk to talk after FeMC makes her last stand using the returnee's magic memento and vents out her hate and anger at her
>Truck-chan persuades FeMC that the trucking is ultimately for the greater good and she walks away convinced
>Final scene is FeMC getting into the truck and slamming down the accelerator towards Truck-chan