Diversity
The Japanese music industry is very diverse, As Japan has been known for their unique stance on pop culture. They make use of (Kawaii) cute to design products, fashion and various culturial things in Japan.
Their usage of cute dances, aestetic design and upbeat music is something that Japan started and really perfected to the point it has created gigantic fanbases around the world.
Due to how diverse the Japense can be, they really have alot of freedom to be creative. That is usually why their work is often different and very dramatic!
The difference is immediatly noticeable upon looking at their work.