Read this: Digimon was first conceived as a virtual pet toy in the vein of Tamagotchis and, as such, took influence from Tamagotchis' cute and round designs. The small areas of the screens (16 by 16 pixels) meant that character designers had to create monsters whose forms would be easily recognizable. As such, many of the early Digimon—including Tyrannomon, the first one ever created—were based on dinosaurs. Many further designs were created by Kenji Watanabe, who was brought in to help with the "X-Antibody" creatures and art for the Digimon collectible card game. Watanabe was one influenced by American comics, which were beginning to gain popularity in Japan, and as such began to make his characters look stronger and "cool." The character creation process, however, has for most of the franchise's history been collaborative and reliant on conversation and brainstorming.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): What were becoming unpopular in Japan?
unanswerable