How many database servers do an online game need for the scale around 100000 users per day?

I don’t need an exact number but I want to know roughly how many MySQL servers do I need to rent if I were to develop an online RPG game that has roughly 100000 users per day (assuming on average 1 hour per user-day)?

To clarify a little bit, I am asking for only the number of MySQL servers and this does not include other API servers. MySQL servers are used to save user save data such as name, level, weapons, inventory .etc.

Also since master servers are more expensive than slave servers so I would like to know how many master servers are needed and how many slaves are needed per master. Again I only need a rough estimation based on experience and feeling, not an exact number.

If anyone has experience about this number and are kind enough to share it I will really appreciate.