Notes:

EDIT: When registering you become a "host" and have to choose one of the main characters(Miia,Papi,Suu,Rachnera,Cerea or Mero). The game is a quiz where you gather "love" points from your chosen character by choosing the correct answer to their question. this then tallies to the overall points that unlock images, etc.

Apparently, there's some kind of game/Quiz that tallies points towards a total and unlocks more images and other stuff as people play it daily.
http://monmusu.tv/family/

This seems to be the page where you register
http://monmusu.tv/family/regist/