There's a tag for black_hair and a tag for blue_hair? Officially, she has dark-blue hair, so the black_hair tag is invalid. The parent and child seem to be identical except different filesizes (same resolution how?) and different sources, both of which lead to invalid pages, as well as this one being tagged as a duplicate and the other being tagged with bad_id.
What happened in this particular case is that someone uploaded a load of artwork to Pixiv (from different artists) and passed them off as their own work.