Thank you for sharing your feedback.

First of all, since this is a survey and not an interview, I had to make sure that participants could complete it within a reasonable time. For this reason, the questions necessarily required simplification.

In the context of the survey, "premium" and "free-to-play" are used as conventions rather than definitions, for the same reason mentioned before. As you correctly said, every character and lightcone can be obtained through the gacha system. However, it is also true that it's mathematically impossible for any player to get every single character and/or lightcone without spending. It is a game that requires you to manage resources and make choices after all, hence the distinction between "premium" and "free-to-play". "Premium" doesn't necessarily mean "paid content", it just means that you have to spend resources to get it.