Rachnera's Tribe

Rachnera's Tribe is a tribe of standard Arachne and the birth tribe of Rachnera Arachnera. The tribe consists of at least thirty members all of whom have a skull-like pattern on their opisthosoma (spider abdomen) as a unifying feature, but each pattern with individual differences.

History
Typical for most Arachne tribes, Rachnera's tribe originally lived in hidden dark places and survived by secretly kidnapping human males in order to reproduce with them (since Arachne are a purely female species). But when the Cultural Exchange Between Species Bill was finally introduced, that changed, as kidnapping humans by Liminals was now a federal offense. However, Rachnera's tribe viewed the new bill with concern, as it is in the nature of the Arachne to hurt others and they were not convinced that humans and Arachne can live together peacefully. For this reason, Rachnera was commissioned as a participant in the culture exchange with the mission to find out whether mutual coexistence is possible.

Finally, in Chapter 67, Rachnera calls a meeting at the Sno Ball Hot Spring Resort, where the leader of the tribe demands an answer from Rachnera on whether humans and Arachne can life together peacefully. Rachnera is not convinced, however, that the other Arachne would actually listen to her, as they often refused new ideas just because they're new and it would therefore be better if they would take part in the onsen event to experience it for themselves, since Rachnera was of the opinion that "stuff like this has a way of working itself out".

Although the other Arachne were still unsure about the idea, they eventually decided to use the onsen. Contrary to their first fears and exactly how as Rachnera had said, the event went off without any problems, as the human onsen participants showed no fear of the Arachne and couples quickly formed between them.

Trivia

 * The leader of Rachnera's tribe is revealed to have a shotacon complex as she remained unfazed by the various bodies of adult men around her in the onsen (and in fact seemed rather annoyed by it) until a male human with a boylike appearance literally fell into her bosom.
 * Neither Kimihito nor his other house guests know anything about Rachnera's mission, as Rachnera never told them about it.
 * If it is common that many Arachne breed with only one human male (as is the case with Lamias), it is possible that many if not all Arachne in Rachnera's tribe are half-sisters or aunts of hers, but as mentioned by the leader, they abduct multiple men unlike the lamias so it's more likely they have an even number of paternal and maternal half-sisters. However, in chapter 67, it doesn't seem as if any of the other Arachne is a blood relative of Rachnera, but that could also be because Okayado deliberately didn't go into detail because it could provide narrative material for another chapter or a whole new story arc.