There is an auto save feature btw and u can just save at the final save point and change character affection and get multiple endings on a single playthrough I think I got 59 endings on 2 runs and have it set up to where I can get more.

Good review, you dont really need to worry about the 81 endings because they are just Hey look what these characters are doing now or which 2 relationships you have. So at the end each characters has an ending with each other character thats how you have 81 endings. Now the only ending you want to see is Claude and Rena together because thats Canon, and you will see there Descendants in star ocean 5 and 6

Good review. One thing to note - there is actually auto saving.