Master – Dragon Ball Xenoverse 2
Just like in the first game, some iconic characters will serve as instructors in Dragon Ball Xenoverse 2. These individuals will mentor you and teach you their own unique super and ultimate attacks. However, you can also make one of these characters your Master, which allows you to actually build a relationship with them.
To do this, after passing the initiation test of whatever Dragon Ball Xenoverse 2 instructor you want, talk to them again and choose the second option: “Be my instructor.” It’s odd, because they already are instructors, but this will actually make them your Master. They’ll then be moved to stand in front of the High School in the lower left corner of Conton City’s map.
Once they’re your master you can build your relationship by taking them on Parallel Quests with you and training with them at the school (just talk to Elder Kai). This will build a meter that you can check by pausing (when in a social space), going to the Play Data tab and moving to the last page. Filling up this meter will unlock Marks that you can show off on your profile by heading back to Play Data, pressing Triangle/Y to edit nickname then pressing R1/RB to edit Marks.
Marks are just pictures of your chosen master showing off their progression. They serve pretty much as a badge of friendship, letting you wear your love for certain characters right on your sleeve.
For more on Dragon Ball Xenoverse 2, make sure to check out our wiki.