Tyria's Cosmosphere is one of the easiest Cosmospheres and doesn't lock based on the heart path of the other two Reyvateils involved. Due to this, you can complete it to 100% as well as 100% of one of the other's involved (but do Tyria's AFTER you accept the confession of the other girl). Her Level 3 deviates into having three different endings and, while they aren't story related, they do help to explain a bit more of Tyria's past.
You may notice that Level 3 has been split into three different spreads. This is because there is a Bad, Normal, and Happy ending, each relating to the choices you may make throughout your re-play of Masakado's daily roles. (1) relates to the Normal ending, (2) goes to the Bad ending, and technically, you have the chance to re-play the Bad ending and make the final choice different, so (3) can be the Happy ending. Tyria will actually tell you she's disappointed and allow you to fix the mistake (the final choice in her house).
Level 3 (1):
Level 3 (2):
Level 3 (3):