So I got a stupid question

what is the difference between a natural aspirated MPI and aisan moter? On a Toyota pickup a got a 22re

 

Mpi = multi-port injection.
Aisin didn't make engines they make parts and accessories.

The 22re is multi-port, one injector per cylinder. Batch fired injection.

 

Just a side note, Aisan is a parts manufacturer that Toyota used and still uses for certain parts, most notably throttle bodies and carburetors (for the older Toyota vehicles): https://www.aisan-ind.co.jp/en/

That company is not to be confused with Aisin, who make brake components, clutch components, cooling fans and fan couplings, oil pumps, water pumps and other parts for Toyota: https://www.aisin.com/product/automotive/