It is not entirely strange observing big brands in cooperation with legendary Japanese cartoons. Even Gucci collaborated with Doraemon back in 2020, but now their Doraemon x Gucci collabs are being sold in premium outlets for a good discount.
It is possible that the airline did this in order to gain more attention towards it. More like a massive marketing campaign. It is said that even the aircraft interiors are decked with Pokemon decor.
This has happened before in the aviation world, Eva Air, the Taiwanese based airline once collaborated with Hello Kitty. The exterior of some Eva Air aircrafts were painted with the popular Japanese cartoon cat.