The following contains spoilers for Episode 6 of Beast Tamer, available for streaming on Crunchyroll with English subtitles.
The most recent Beast Tamer episode featured a continuation of Rein's inadvertent mission to gather every individual of the ultimate species. Kanade, a cat spirit, joined the party first, followed by Tania, a dragonoid, and Sora, a fairy, seems to be the next female to join. So far, every female member in the party has played a stereotypical role, and Sora appears to be no exception.
While Tania is more of a traditional tsundere, Kanade openly clings to Rein, Sora's calm nature seems to place her in the stereotype of the shy girl. It's not a given that Sora would fall in love with Rein, but it's difficult to see her not doing so when he accepts a perilous task for her.
Sora hated humans until Ren appeared
As a member of the fairy race, Sora, in her own words, views humans as her natural enemy. Humans cut down forests for resources, and for fairies who use the forest for their homes, this naturally puts them at odds with one another. To combat this, the fairies hid their home in the Lost Woods with magic, causing all who enter to walk in circles, unable to find the true path to their home.
The fairies of the Lost Woods do, however, keep a powerful artifact under their protection: the Shield of Truth. This shield was originally the reason Rein and his party came to the forest after being told to by Arios, the leader of Rein's former party, as they were unable to reach it. The tale of the shield states that it is held by a powerful monster, but that's revealed to be a lie told to keep humans away.
The only person who can save Sora is Ren
What isn't a lie, however, is the fact that Sora needs Rein's help. Sora and her sister Luna were originally the ones meant to guard the Lost Woods against intruders, but they left their post one day and paid the price for it. A Shadow Knight, a powerful subordinate in the Demon King's army, captured her sister, and she has been held captive ever since.
While fairies are more powerful than even dragonoids when it comes to magic, Shadow Knights have an ability that nullifies all magic used against them, rendering the sisters' abilities completely useless. When Sora told her village chief what happened, she told her that there was nothing they could do. Hopeless, Sora remained at her guard post, waiting for someone to come and rescue both her and her sister.
Enter Rein and his party. With Rein's compassion and gentle nature, he was able to break down the walls around Sora, causing her to confess everything to him, and naturally, he accepted her request without hesitation. Sora and Luna have appeared in multiple trailers for the show, as well as the opening sequence, so it's all but guaranteed that they'll be joining the party in the future, and likely within the next episode or two.