"Yahoo! Japan" is a different company altogether from this Yahoo though. They were founded by the original Yahoo! and SoftBank. After the original Yahoo was mostly acquired by Verizon, the remains of it were spun into a company of its own "Altaba", which was later acquired by SoftBank and then made a part of Z-Holdings a joint venture of SoftBank and the Korean Naver Corporation. And just recently it was announced that the individual companies of Z-Holdings will be merged into one big company. The Japanese internet business is quite the rabbit hole! (Disclaimer, I work for LINE Corp, another subsidiary of Z-Holdings)