In the Ancient Forests, 29 years after the death of the hero Himmel, the episode begins with a conversation between Frieren and Sein, a villager from the Ancient Forests. Sein recalls his childhood dream of becoming an adventurer and regrets not fulfilling it. He recounts how he got stuck in a swamp while gathering herbs for his village's harvest festival, leading to a humorous interaction with Frieren, who hesitates to help him because of his dirty hands.

Frieren, Fern, and Stark continue their journey to reach a large city where they can stock up on supplies. Sein warns them about the dangerous poisonous creatures in the area. Shortly after, Stark is bitten by one of these creatures, triggering a series of events that force them to return to the village for treatment.

In the village, Sein's brother, a priest, treats Stark's poison. It turns out that Sein's brother is an exceptional priest recognized by the holy capital. Frieren learns about Sein's past and his unfulfilled desire to become an adventurer. Sein's brother wishes for Sein to leave the village and forge his own path.

The episode deals with regret and the consequences of decisions made in the past. Sein reflects on his choice not to become an adventurer and the life he could have led. Frieren contemplates her own past decisions, particularly her hesitation to join Himmel on the quest to defeat the Demon King.

Frieren decides to invite Sein to join the group, though he initially resists, unwilling to leave his village and his brother behind. The episode ends with Sein accepting the invitation, motivated by the desire to reunite with his childhood friend and fulfill his dream of adventure.