Examples of Harikeshiya and Arjunmali and the yaksha which entered their body. So are the devi/devata the doer of our karma?

In Jain Dharma, devi/devata/yaksha are not the real doer of your karma.

The core Jain principle is:

• A soul binds karma by its own actions, thoughts, speech, and passions like anger, pride, deceit, and greed.
• No deva or yaksha can create your karma for you.
• They may sometimes act as an instrumental cause (nimitta) in a situation, but the actual bondage and fruition of karma belong to your own soul.

About stories like Harikeshi Muni and Arjunmali

Such narratives show that celestial beings may:

• protect a saint,
• help in a situation,
• or create a visible effect in the world.

But even in those stories, Jain understanding remains:

• the soul itself is responsible for its karmic bondage, and
• the deva is not the ultimate creator of that karma.

Important Jain view

Even if a yaksha enters a body or a deva appears to influence an event, that does not mean:

• they become the owner of your karma,
• they are the final judge of your destiny,
• or they can cancel your karmic law.

Karma in Jainism is self-earned and self-bound. Devas may be helpers, witnesses, or auxiliary causes, but not the doer of your karma.

Simple conclusion

No — devi/devata are not the doer of our karma in Jainism. We ourselves are the doer of our karma through our own inner states and actions.

If you want, I can also explain the story of Harikeshi Muni and Arjunmali from a Jain karmic perspective in a simple way.