Hyakuya Orphanage Family

The Hyakuya Orphanage Family refers to the children that Yūichirō Hyakuya and Mikaela Hyakuya lived with at the Hyakuya Orphanage in the Seraph of the End series. Within the manga, there are various unnamed orphans forming a part of the group. Within the anime, members of the family have names revealed.

The director of the orphanage had a policy that everyone there was family, so members share the same Hyakuya name after the orphanage, yet the children are not biologically related to one another.

They were neither formally adopted when they were captured by vampires after the apocalypse event and so are not adoptive siblings. However they maintained that they were family and continued to live together in the vampire city, Sanguinem, underneath Kyoto. There and beyond they would uphold that they were family.

Hyakuya Orphanage Family members
In alphabetical order, named members are:

Akane Hyakuya
She helped cook food for the family as they lived together.

Story
As the apocalypse event is underway the orphans make their way back to the orphanage and are captured by vampires who are gathering the remaining humans to secure their blood as a food source. After living underground in livestock clothing for four years it is remembered how Yu joined the orphanage and met Mika first.

The family members join in an escape plan arranged by Mika, Yu and Akane however at the exit it is revealed as a trap set by a vampire noble, seventh progenitor Ferid Bathory. The orphans are all murdered by the supernaturally strong vampire aside from Yu.

They are referred to as seraphs by third progenitor Krul Tepes and the Hyakuya Sect was revealed as a cult where abandoned children were experimented on.