Materia Music takes down Neuro's DELTARUNE and UNDERTALE Covers

Materia Music Publishing has begun issuing copyright strikes against videos connected to Neuro-sama that use music from Undertale and Deltarune. Clippers such as Kraul have received full YouTube strikes for videos that simply used game music as background audio.

According to posts from Kraul, one of the strikes targeted a Neuro clip that had "Bonetrousle," a popular Undertale song, added during editing. Kraul said the music was manually inserted after the stream and was not part of Neuro-sama’s original broadcast.

They gave my channel a full copyright strike because I manually added Bonetrousle as background music to a Neuro-sama video I edited. It wasn’t in the original stream, and the song was never used for training, generation, remixing, or any AI process. This is absurd. https://t.co/GGeE9NBPG3
— Kraul (@Kraul_en) July 22, 2026

Kraul also stated that the song was not used to train an AI model, generate new music, or create any AI content. It was simply added as background music in a clip. Despite this, Materia Music still issued a full copyright strike.

Following the backlash, Materia Music added the following to their licensing policy, which states:

"We do not permit our music to be used in conjunction with any AI content or AI personas/vtubers/agents, on any platform."

The company says that unauthorized uses may lead to DMCA takedowns, copyright strikes, or further action.

Materia Music's Policy on AI

Materia Music has published detailed rules for using music from Undertale and Deltarune on YouTube. In many cases, non-commercial fan content is allowed, and videos may receive normal Content ID claims instead of strikes. These claims usually let the video stay online while giving credit or revenue to the rights holder.

However, Materia draws a much stricter line when AI is involved.

According to its policy, the company does not allow its music to be used with:

AI VTubers and AI personalities. (which was added after striking Neuro content)
AI-generated videos.
AI agents and similar technologies.
AI systems trained using copyrighted music.

The company also advises creators to get proper licenses for covers and to avoid AI tools that learn from its music.

Why Is Materia Involved?

Materia Music handles publishing and rights management for the soundtracks of Undertale and Deltarune. Its job includes protecting Toby Fox's music from unauthorized use and making sure copyright rules are enforced.

Because the games became extremely popular, their soundtracks are heavily monitored on platforms like YouTube. Over the years, many videos using the music have been hit with Content ID claims.

This has caused controversy in the fan community before. Fan projects, soundtrack uploads, and even games inspired by Undertale have sometimes received copyright claims. In some cases, those claims were later removed after reviews or disputes.

An undertale remix on YouTube taken down by Materia Music

Toby Fox himself has previously encouraged fans to challenge incorrect claims, noting that the huge popularity of the music has led to stricter enforcement.

Reactions

The swarm, clippers and fans alike, have criticized the strikes. Their main argument is that the affected videos were not AI-generated and did not use the music to train any AI system. Instead, they were ordinary covers made by PB, a human, that happened to feature Neuro, an AI VTuber.

Some also believe that Materia's public statement about AI was posted only after the strikes had already been issued, making the policy feel reactive rather than clearly communicated beforehand.

Vedal's Response

On June 4th, 2025, the official Neuro-sama clips channel posted a video titled "Neuro Spoils DELTARUNE Chapter 3 & 4 Before Release". It was a clip where Neuro talks about Deltarune. It has since been taken down by Materia which posed a real risk to the official YouTube channel since some videos have Undertale and Deltarune music present.

An discord embed of the clip taken down by Materia

After this strike, Vedal decided to respond on the matter on a community thread advocating for removal of all official clips (including shorts and long-form) that have Undertale and Deltarune songs. He stated that he is aware of the situation and is ongoing private talks with Materia to resolve the matter. As of writing this article, this issue is still ongoing and either side has yet to respond.