Truck-kun summoning and Fantasy world then? Most isekai's there but alright. Plus you don't know how ridiculous that could be in the right circumstances. So you didn't make that simple at all. 

Now it's time to decide if there there is a system or not. I mean it's fun to have an info screen show you your stats or skills, or a biochip AI to help you analyze stuff. 

Stat System; Skill System, Basic System, Proficiencies System, Biochip AI (Consider this out as sci-fi wasn't chosen), Knowledge System; Adventurers Guild Card (System Card); or No System at all

Don't worry about not getting the one you wanted, as All of these systems (or not) will make things fun.