In #Japan, it is possible for a company to use and share personal information for an internal usage among the companies which have the same parent one, as long as you have once got a consent. This is one of the important differences between GDPR and The Japan Act on the Protection of Personal Information, also known as APPI.

So, if you have agreed that your private information to be used to “improve their services”, you have basically given the green light to let them use it for whatever objects which they regard improve them, including to train #ai model by machine learning.

Also, the usage of data for machine learning is not limited by the copyright of the data. See: https://coinpost.jp/?p=465637

That's why Japan is called as the heaven for machine learning by the private companies, whereas it is privacy hell for the general population, compensated by nothing for letting them use the data for their business.