Writing on the Seethe as they emerge.

 

I wonder what it says?

Soh taking damage in the toxic pools.

Maskless:

"Who is Tenko?" Tsuba Guards and Villager roles.

Update: A new post on Tenko is here: Tenko's Sacrifice: Benzaiten

The Goddess Symbol and Purification.

When Yoshiro activates the symbol, it pulls defilement into it and transfers it into Yoshiro.

Her map symbol is a katashiro, designed to absorb impurities.

She stands atop the symbol as this is the defilement's final destination: her body.

It resembles the Kaleidoscope effect: also called Sun Halo or Moon Halo. (Yoshiro and Soh)

Sun Halo

Moon Halo

When you defeat Festering Seethes, Yoshiro pulls in all of the defilement and in doing so, purifies it.

When Yoshiro falls in battle, all of the impurity she holds within bursts forth from her in what appears to be an endless stream.

We(the screen) are also covered in impurity.

Soh's mask has the impurity pattern on it and we are led to believe the Maiden eventually becomes the next Messenger. 

I don't think the Maiden becomes the Messenger the way we think she does. It's better to say that the Maiden is no more and has fused with the Goddess entirely. There is only the Goddess who sends herself as the next Messenger.

Could Soh's mask have been clear originally but through fusing with these Maidens, it took on this pattern, symbolizing the Goddess steadily becoming cursed?

A little more on this symbol:

It's officially called 'Shrine Symbol' according to Steam.

In the middle is the sword that is associated with the Goddess, as seen here:

Yoshiro acts as an abode and shrine for the Goddess, as well as a katashiro. 

If you look at the symbol, then look at the following image, don't you think it's a visual representation of what Yoshiro is meant to do?

The defilement core.

Centering it allows Yoshiro to regain health.

But what is it?

When Yoshiro is unwell, Soh loses her body completely.

But when she 'dies' or when Yoshiro loses all her health, a body is left behind and this strange substance is all over her mask before she falls.

It looks almost similar to the defilement core.

Since we're helping Yoshiro purify the Torii gate, is the defilement core a form of Soh's?

It might be linked to Yoshiro holding impurity within her.

!! I decided to check what Yoshiro looks like when she's attacked.

It might be the impurity from the Seethe themselves as their attacks cause a build up of impurity, resulting in defilement. You can even see the Seethe's strike is an arc of impurity.

Cursed Soh's wheel.

Cursed Soh's wheel is called '光輪'. (According to official merchandise)

In-game, it's called 'kouhai'. 光背.

It's a halo!

A look at the Otherworldly Venture Drop Box.

They drop from tough enemies and Kagokaburi. They make a cute little giggling sound, too!

A yellow orb? It looks like a corrupted oyster. A pearl...

More on the DLC here:

Venturing in...(A million in Otherworldly Venture and some tips)

Otherworldly Venture: rewards and thoughts.