I recommend going from route 1 because it links onto route 2 pretty nicely. :)

Route 1

-XXX-

… we need to clarify your real gender. It would be unseemly and deserving of death, if we were, and are continuing to address the great Ainz-sama with the wrong pronouns.

Excuse me for my brashness, but are you male or female? Man or woman? Or perhaps, an exalted one such as you, will be forever beyond my realm of understanding.

Huh…? Wa…? I… Ga… Um…

I'm a male. A Japanese man to be exact!

What else can I be?

I acknowledge the existence of hermaphrodites, especially for demons, but are there more than three sexes or genders?

Just where are we going wi…

My wise creator, Ulbert Alain Odle-sama, once had an argument with Touch Me-sama about the rights of the Attack Helicopter gender. Ulbert-sama deemed their growing faction evil and fakers, whereas Touch Me-sama believed in equality and justice. I find this to be deeply intriguing.

Please impart me some divine knowledge of the Forty-One Supreme Beings.

How does this…

W… w… what am I…

W… why… is this…

[O.o)- ] Oi! Ulbert! Touch Me! Look at what your doing has led to! You two have some serious explaining to do!

How the heck am I supposed to explain such a thing to your children!?

Why were you two even arguing about that in the first place?

Hmmm…

Ulbert, did you get into some messy affairs? You seem to be a magnet for them.

No, no, no.

Touch Me's personality is just as likely to…

-XXX-

"Oh! My dear Ojou-sama!" exclaimed Pandora's Actor.

This sudden exclamation from behind the heavy doors briefly interrupted Ainz's thoughts. Pandora's Actor probably has taken a ridiculous talking pose as usual as he continued speaking.

"Meine dame*1 Shizu, are you here to drop in your missionbericht*2, too? I've been thinking of you ever since you graced us with your lovely presence at the meeting."

Shizu grabs onto Pandora's Actor's right arm.

"Oh…? How frisky of you to passionately grab onto me. What can I say? A gentleman's charm sure is troubling to…"

"Analysing… Shizu identifies this unit's right arm to be an obstruction to the submission box. Shizu will immediately amputate it to complete objective faster."

Bzzzzzz…

"Eh? What is it, my sweet...? Gya! Mein Führer*…!"

-XXX-

Pandora's Actor… Ignore him, ignore him… He probably deserved it…

Maybe I shouldn't be so quick in pointing fingers at Ulbert and Touch Me.

Better concentrate on Demiurges letter first.

Ahhh! How can I?

I just realised how terrible the project's name sounded after Pandora's Actor said it.

Another shameful past to add...

No, perhaps, you were testing me all along, Ainz-sama. Let me show you my growth and present to you the fruits of my research and my experiments.

I've noticed your hands when you first handed out the Ring of Ainz Ooal Gown…

[3 o.o 3] M… my hands?

… followed by your skeletal structure during the bath, namely your bi-acromial length and pelvic structure.

Ehh…

Males tend to have longer ring finger than index finger. Females tend to have similar finger length between index and ring finger. When males or females are more interested in the same sex, the opposite measurements tend to be more common.

Average male height is around 176 centimetres (5ft 10in) and 160 centimetres (5ft 3in). However, more importantly, the ratio of shoulder width to height is around 0.26 for males and 0.23 for females.

There are also four types of pelvis I have observed: android, anthropoid, gynaecoid and platypelloid. Android and anthropoid are more commonly found in males, while gynaecoid and platypelloid are more commonly found in females.

Female feet tend to be smaller in proportion to height than males. Males have similar torso length to leg length. Forgive me, but I have not finished analysing these two points.

Ainz-sama, please allow this one the courtesy of announcing your majestic figure. You have: a similar finger length between index and ring finger, the height of 177 centimetres, a shoulder width to height ratio of 0.24, and a gynaecoid pelvis.

A very feminine like structure, except your height.

[~.~] This is... triggering me beyond the realm of my body complexity.

Did you get this information from Nazarick's library? To think you would look for this kind of information there.

On the other hand, it's actually quite interesting… but I don't see how you can consolidate anything from this.

Actually... how the hell did you manage to get my measurements so precise? There's no copy of that in the library is there!?

Courtesy of Albedo to provide me the information when I implied I was going to get you a customised gift.

Haa... The Satoru Suzuki within me is tired.

Demiurge, I bet you were grinning your way through this...

Albedo... I'm... I'm just going to overlook this ever happened... Albedo is kind of a special case on her own...

Furthermore…

You have more?

… sometimes you display a very feminine behaviour, almost motherly, towards Mare and Aura.

[=I] At least say fatherly, Demiurge…

Are you trying to straight-up deny my manhood?

My voice… what about my voice?

It's deep and masculine, is it not?

The voice you have is completely irrelevant. We all know how thick bones resonate best with deeper voices, such as yours.

The evidence is more complete than ever when you add the abundance of female clothing.

[-.-;] The female clothing is for collection purposes… you know…?

I do not think a proper ruler as great as Ainz-sama, who acts with precision and purpose, would collect items of insignificant value.

[:L] Geku.

Only adult males with dark perversions, such as some humans I observed, will collect and possess unsightly items for their sex and gender.

[X] Bam!

[(-'T.T)- lXl ] No…! M… my mental escape door… Please, don't close on me!

At first, I thought the clothes could've been from your dear previous lovers or for your potential future lovers, but since you nonchalantly gave it to Sebas' pet, I have ruled out that possibility.

[ /(T.T)\ ] Stop… stop! I'm already dead.

The only way I can be any more dead than an undead… is being an unanimated skeleton.

Ainz-sama, even if you are a female ruler, I still believe…

I… I…

Please select how Ainz responds and proceed:

1. Kyarun… I am actually Ainz-chan, a magical lichess… (To route 5)

2. I don't understand how this would affect anything significant in Nazarick… (To route 2)

3. I… It's not like I enjoy collecting or anything. Hmpf! Regardless, we should plan a celebration for my success! (To Overlord: The Guardian's Plot written by PervySageChuck)

Measurements based off old charts.

Tell me if there is something wrong.

German for:

*1 My lady

*2 Mission report

*3 My commander