It is Ifrit, the Greater Elemental of Fire.

What is the name of the Greater Elemental Spirit that resides within Shizue?

Rimuru's nation is called the Jura Tempest Federation, or just Tempest for short. It is also sometimes referred to as Rimuru

What is Rimuru's nation called?

What 2 unique skills did Rimuru reincarnate with?

The Ultimate Metal, after being analysed by Raphael, was called Hihiirokane. Rimuru's sword is comprised of this metal.

LN QUESTION - What is the name for the "Ultimate Metal?"

Great Sage, after Harvest Festival, evolved into Ultimate Skill: Lord of Wisdom, Raphael.

What is the full name of Rimuru's Ultimate Skill Raphael?

Guy Crimson, after witnessing the Demon Lords lose 3 members and gaining Rimuru, decided to let him name the Demon Lords. Rimuru named them the Octagram.

This is the only walpurgis currently in the anime.

What are the Demon Lords known as after Walpurgis?

Which True Dragon did Rimuru encounter during Episode One?

Yuuki, after defeating Mariabell, absorbed Greed from her. 

LN QUESTION - What skill did Yuuki steal from Mariabell?

Masayuki's Unique Skill is called Chosen One, or Chosen Hero.

What is Honjou Masayuki's Unique Skill called?

There are Eight, hence the name, Octagram.

Let's see if you've been paying attention.

There are Nine Demon Lords after Walpurgis

Shion's "Master Chef", lets her manipulate the probability of her attacks hitting her opponent, to the point at which she can enable her attacks to hit 100% of the time, breaking through any barrier that stands in her way.

What is the effect of Shion's Unique Skill (Gift), Master Chef?

Before taking Greed from Mariabell?

LN QUESTION - What Unique Skill does Yuuki have?

This quiz will go over things from the anime, as well as a few things from Volume 10 and Volume 11 of the LN. So be warned, spoilers are ahead.