Nico Nico Douga's Shared NG Feature (NG共有機能) blocks poorly-rated, or "NG", comments from being displayed on videos. The girl at right has her Shared NG Level preference set to "weak", which blocks the lowest-scoring tier of NG comments. Presumably, this has made the student sitting to her right invisible to her.
NG Shared: Weak— 31st (Friday)Contemporary LiteraturePhotos: 3/12 (Wed) —— unite!!1 Math B
2 P.E.: Substitute —
3 Contemporary Literature
4 Geography/History
5 Electives: Calligraphy → Pool