Currently, the tallest building in Japan is Abeno Harukas in Osaka. It is 300 meters tall. I enjoyed watching it slowly going up and up and I walked past it nearly every Friday for a couple of years around 2013 or so. I even made a video about it:
https://youtu.be/YP0H-vuWMU8
Now today I read where: “Mitsubishi Estate has unveiled plans for the Tokyo Torch, a 390-meter (1,280-foot), 67-story skyscraper that will become the tallest office building in the country, and the second-tallest structure behind the 630-meter (2,080 ft) Tokyo Skytree.” https://newatlas.com/architecture/tokyo-torch/
But that won’t be completed until 2027, so I still have a few more years left to amaze tourists, like the Hong Kong lady, who refused to believe me when I pointed to Harukas and said it was the tallest building in Japan. That might be because the little area of Hong Kong has 6 buildings that are taller!