Persona 5 has multiple endings, but Royal adds a few new endings. To get to the third semester (aka royal’s content) you only need to reach Rank 9 with Maruki before the cutoff date. But to get the best ending you need to focus on 3 confidants.
Persona 5 Royal Best Ending
You need to reach Rank 9 with Maruki and Rank 8 with Akechi before the 18th of November, and reach rank 5 with Kasumi before the 18th of December.
After you reach these ranks, you have to make specific dialogue options to continue to the third semester. Very VERY minor spoiler warning below. (Does not spoil what happens, but does tell you the date they happen on.)
- November 20th: You’ll want to play dumb, select “No” or “Never heard of them” and then “There were no such people” on the question after.
- December 24th: “I refuse” is the answer that will take you into Royal’s third semester.
- February 2nd: You’ll want to refuse again. This is the last of the major choices.
Important
Failing to max Akechi or Kasumi’s Confidant before the deadline doesn’t lock them out of your party in the 3rd semester.
In Akechi’s case, you’ll lose out on the extra scene during the ending (fair enough, this can be considered essential for it to be the best ending), and his 3rd awakening.
In Kasumi’s case, you’re just not allowed to rank up her Confidant any further, which results in no 2nd or 3rd awakening, but doesn’t have any impact on the ending at all.