So I don't know if you were meaning to imply this, but it really sounds like this Naruto is not from the Ninja world. I would like to know (If you want to, you don't have to, especially if it pertains to later in the story) why you imply that he's just a normal guy from Earth. Anyways, this sounds super interesting, a way to enjoy smut but still having a good story line (unlike a lot of cultured anime out there).

Mt Lady (Boku No Hero) in Silver, because while she is a pro hero, she's still a rookie. I believe that she would absolutely adore the attention she would get in the tournament, because it would allow her to show her "assets" much more freely and she is great at putting a show for an audience. Not to mention, her gigantifiction quirk would be a great advantage in any match, considering how difficult it must be to have sex with a giantess.

(If this review is repeated I'm sorry, it's just that I posted this in chapter one but it hasn't updated or shown my review).

Mt Lady (Boku No Hero) in Gold, since she may be a pro hero, but she is still a rookie. And I can imagine that she would absolutely adore the attention she gets in the tournament considering she can show her "assets" freely. I also believe that her gigantification quirk would be very beneficial to her in a match. Having sex with a giant would be difficult after all.

Mwhahahaha, Momo better get started on a new harem plan for her new boy toy in the future.

Maybe Magi morgianna and myron for bronce i doy t that they are experiented in sex and you alredy know the characthers

I would like to see Mirko because you owe us a scene between them. It could be a reference to your other story.
Momo (Boku no hero) could be bronze since he is a beginner.
Esdeath (akame ga kill) could of a top champion, but watches the novices looking for a promising young woman for herself. (in anime she likes young man for her to train him the way she likes)
Mirijane and Erza (Fairy Tail) they can enter young as rivals.
Tsunade (Bronze) Seriously funny a woman like her is innocent about sex.
Yoruchi (bleach) silver could go in search of something interesting.
Erina Nakiri (food wars) known as the language of God (bronze) for being naive over everything else.

A new story again, hmmm i’m starting to dislike you. I’ve read your stories since 2014 and almost all of them are unfinished. Until now i’ve been waiting for an update of at least one of your stories like SKU, Sun God or the Cat’s Bae but nope, nothing.
I’ve had enough playing the waiting games. I’m done.

Peace

Yeah Momo.

How about Nezuko from demon slayer? I think she'll probably be silver or gold since she's a demon so she would be super strong and have a lot of endurance.

At first I was like: "wait, isn't 6 inches a bit small?" And then it went to me that it's 15 cm - not small, but not big either. Different measurement units can be confusing XD
Wonder though why this alien species need champions to have sex, so that their species can continue? Mr. Doctor (it's Strange... maybe XD) ignited a spark of interest in me XD

Now, Bronze rank champions... I have few ideas:

Tamaki Kotatsu, Fire Force, Bronze Rank (duh) - Tamaki have interesting trait known as Lucky Lecher Syndrome, which is making her either 1.) lost parts (or all) of her clothes, or 2.) being forced into perverted situation out of nowhere (like groping or strange positions) even if all what she wanted was to grab some item close to some man XD
She could end in alien world by accident, through acquiring Adolla Link and being transported through Adolla dimension (sort of a Hell) into this planet, where to make money she needed to became a champion.
Also, she can create and manipulate flames in form of cat ears and twin tails :3

Maki Oze, Fire Force, Bronze Rank - Maki is from the same Fire Force squad as Tamaki, so they know each other very well. Maki however have only flowers in her brain - thinking nonstop about cute and sweet things.
She could end in alien world together with Tamaki, through Adolla Link.
Unlike Tamaki, she cannot create flames, but can control them with much better precision, which she may use to control temperature of her partners bodies to increase their pleasure (and win quicker by exausting them with it).

Sona Sitri, DxD, Bronze Rank - Sona could enter tournament just recently, after she learn that her sister is a champion there. Being very strict person, she will be very dominating during her intercourse, though fairly unexperienced, which may result into situations, whe it's she who's dominated.
And she could use her water magic to milk out her partners, or use water like limbs, to wash and massage them and herself.

(This character may contains spoilers for Black Clover)
Secre (Nero), Black Clover, Bronze Rank - Secre is a human girls who, by use of too powerful Forbidden Magic, was cursed into a bird, and only recently manage to turn back into human, though she have small black horns on her head.
After battle with Word Magic Devil she could slip into void of Shadow aplace and awake in alien world, where she decided to stay, because her friend and master (First Magic Emperor) has died and she has no longer purpose to live in her original world.
She use Sealing Magic, which can simply close and open things, bu after her arrival to alien world, could developed into sexual use. For example: she could use it to open her womb impossibly widely, to allow her partners enter her deepest parts, or she can close or opern their eggs to allow more sperm to came out.

That's it, I cannot think of anymore girls for now, and it's getting late. Hope girls will be useful (that sounds terrible XD).
Btw. will we get a full list of girls? Or will you inform those who's girls qualified? Because I'm really curious who made it, and did my proposed girls made it XD
Ps. I'm still impressed of how much you write... seriously, I'm shocked how good you are at thinking and making stories... I'm kind of envious of that XD

Aoi Ichijō From High School Prodigies Have It Easy Even In Another World would be an excellent choice. A young woman who seems very driven and strong, yet is more than likely inexperienced would make for an excellent Bronze. Hell, two of her friends are basically sharks.

Alex Benedetto from Gangsta, Princess Allura and Haggar from Netflix's Voltron: Legendary Defender, How to train your dragon Series: Astrid Hofferson, Heather, Mala and Atali, Gogo Tomago\Honey Lemon and Cass Hamada from Big Hero 6. Just to drop a few names you could use if ya like

Thx for the chapter, I really appreciate the work you put into your stories.

Garnet, Widow and Makina from the Dragonaught: The Resonance anime is who I am putting forward. As for their rank, Gold for Garnet, because she; in the anime is very military trained and battle hardened.
Whereas Makina, I would possibly put her at Gold rank after she looks like she does later in the anime. But Makina would start out as Silver due to her not being as militarily and battle hardened as Garnet.

Widow I would also possibly and more likely have at Gold rank with Garnet due to her being as battle hardened as her but she tends to be slightly more like Makina in that you could put her at the Silver rank as well. Another is there are literally so few fanfics of this series, and even more scarce crossovers w/ the Naruto anime.

Awesome stuff man keep up the awesome work and keep updating thanks.