That was indeed rather cute. I'm glad this pair got so popular. From what I hear there is a good handful of artists planning to do Akane x Rikka doujin at summer comiket, as well.

This is actually just one part of a crossover(?) doujin

From just looking at the author's pixiv, it doesn't seem to be a cross over, just a few independent stories.

Interesting. So you say that Akane in real world was afraid to return IRL Rikka feeling. Hence she created this world where Rikka unconditionally love her by default?

That's A LOT of assuming, and I don't know if I'd go that far. But Akane for sure cares Rikka a lot and isn't really indifferent.

In the anime, Rikka is gay toward Akane 100%. The mixing. The gift. The ‘you are born to love me’
Unfortunately Akane acts very indifferent toward Rikka. Maybe she fond of her more than any other characters, but the mutual romantic affection is not quite there

Interviews out right confirmed that Rikka is the only person in the computer world that Akane loves.
https://i.imgur.com/UtJnXDf.jpg

Also, in the most recent interviews in Mook Magazine it tells is that the first scene of the ED is actually in the real world, and we're seeing real world Akane and Rikka. The director also noted that it's not a coincidence that Rikka's Mom, Alexis, and Gridman all have yellow eyes. This is telling us that Rikka's mom is a being from the hyper world. Which means she can travel between the computer world and real world.

It's fairly safe to assume that Rikka from the real world and Rikka in the digital world are one and the same, and that her mom brought her there to save Akane.

Terribly sorry but, what are these "Raffle prize balls"? Google did't help me...

In Japan they have this sort of lottery thing and there's a bunch of balls inside a container, you spin it around until a ball comes out, and you win prizes based on which ball you got.

https://onlynativejapan.com/2013/01/13/gara-gara-the-japanese-unique-raffle-campaign-machine/436

Hah, poor Yuta.
Get's tricked into thinking he's going on date.
Girl just wanted to dress him up in girls clothes.
The girl he likes, likes another girl.

This was absolutely amazing. It honestly deserves a full series.

Maybe you guys haven't actually read the novels that are a sequel to the manga, but these two end up living together again, as Yoruichi takes over that soul society special opts team again, and Soi Fon is her right hand, or whatever.

Edit: wait... This must be the continuation for this

It's actually a continuation of https://dynasty-scans.com/images/11303
The one you linked is them in the nurse's office. This one here is in Rikka's room.