Eris Is One of Rudeus' Fiercest Allies in 'Mushoku Tensei' — Why Did She Leave?

Spoiler alert! This article contains plot points for Season 1 of Mushoku Tensei.

The Summer 2023 anime season is chock-full of both exciting new premieres and highly anticipated returning shows. Among the latter, Mushoku Tensei: Jobless Reincarnation comes back after a bit of a lengthy hiatus for an all-new second season. Based on the Japanese light novel series from Rifujin na Magonote, the isekai series follows a modern-day man who finds himself jobless and severely depressed.

After losing his life while protecting a group of teens from an oncoming truck, he is inadvertently reincarnated into a medieval world of sorcery as Rudeus Greyrat. Having retained his skills from his past life while becoming highly proficient in magic, he tries to carve out a new life for himself in this strange new world as he becomes embroiled in all sorts of conflicts.

Along his journey, he becomes close allies with Eris Boreas Greyrat. But she leaves Rudeus at the end of Season 1. Let's break down why.

Eris Boreas Greyrat is a noble-born heiress and a very distant relative of Rudeus. She has a short temper and shy tendencies, but she is shown to be incredibly proficient with swords. Eventually, Rudeus even becomes Eris' teacher as he imparts his skills in magic to her.

They become even closer as they begin traveling together, having been displaced from their nation after a magic assault destroys their home and brutalizes their people. He resolves to protect Eris and his newfound allies as they make their way home.

Throughout his years-long journey, Rudeus actually ends up sparking several different romances in a sort of polygamous relationship. Eventually, Eris takes part in this as well. Having gone through several ups and downs with each other throughout their travels, they eventually come to an emotional understanding and grow deep feelings for each other.

In fact, it's those deep feelings that actually explain why Eris eventually leaves his side.

Eris has been witness to many of Rudeus' escapades, including his harrowing fight with the Dragon God Orsted. Having felt that she failed to protect him from his near-death experience, she ultimately resolved to do whatever it takes to ensure she can protect him more effectively.

To that end, she all but breaks his heart. After spending the night together with Rudeus, Eris leaves quietly into the night.

There was no malicious intent, however. She actually decided to leave on her own journey fellow swords-woman Ghislaine in order to become as strong as she feels that she needs to be to protect him.

Her departure, however, left a deep emotional wound on Rudeus. Luckily, he's able to find it in himself to press forward while awaiting her return. And his newfound confidence couldn't come at a better time, considering that the journey will only get harder in the second season.

Mushoku Tensei is currently streaming on Crunchyroll. New episodes premiere every Monday.