Correct use "related_name" in Django

I surely have not formulated the question correctly, I explain what the problem is.

I have in the model:

models.py

class Muro(models.Model):

    tema = models.ForeignKey(Tematica,
        on_delete=models.CASCADE,
        verbose_name="Tematica",
    )
    ...

class Historias(models.Model):

    muro = models.ForeignKey(Muro,
        on_delete=models.CASCADE,
        verbose_name="Muro",
    )
    ...


class Comentarios(models.Model):

    historia = models.ForeignKey(Historias,
        on_delete=models.CASCADE,
        verbose_name="Historia",
    )
    ...

In my application I have a wall by theme, each theme has its stories, then in each story I want to add comments.

I pass the pk through the url and filter the stories of each wall, the problem is when I want to filter the comments of each story, the pk no longer serves me, since I would need to filter by the pk of each story.

in my view I have:

views.py

def muro(request, pk):

    cabeceraMuro = Muro.objects.get(pk=pk) 
    historias = Historias.objects.filter(muro__pk=pk)
    comentarios = Comentarios.objects.filter(historia__muro__pk=pk)

    context = {
        'cabeceraMuro': cabeceraMuro,
        'historias': historias,
        'comentarios': comentarios,
    }
    return render(request, 'muro.html', context)

The header data of the wall all ok, in the stories of the wall all ok, but the comments are the same in all the stories, I can not get it to only show the comments that belong to each story only.

In my template:

muro.html

{% for historia in historias %}

<h1>Historia</h1>
...
<p>{{ historia.nombre }}</p>
<p>...</p>
...

<h3>Comentarios de la historia</h3>

{% for coment in comentarios %}
...
<p>{{ coment.comentario }}</p>
<p>...</p>
...

{% endfor %}

{% endfor %}

I'm stuck at this point. I have read in the django documentation about prefetch_related () I have tried with the examples, but I do not get it, on the contrary, I mix the comments of each theme.

I appreciate any help, thanks in advance.