If you mean the special slaves (One per each race), you need to unlock them by increasing the likability of the 4 main girls in which they'll give them for you free of charge
If you mean the upcoming game DLC, it's currently in the works, the developer seems to be updating their ci-en regularly with DLC developement notes (Currently at #6 - had to use translator since I'm beginner at Japanese haha)
It is super promising from what I got, here's some info:
1) The developer is planning to release the DLC in January 2023 (So 2 months of waiting) with a rough early estimate release on December 2022. (Dev Note #4), the DLC will be priced at 770 JP¥
2) A new NPC (Main girl) will be introduced with the name
"Barbara" tho I don't know what her purpose is, she is themed after SM so probably related to that. (Dev note #2)
3) Two new special slaves will be added, a catgirl named
"Nero" and sheep girl named
"Anna" (Dev note #1)
4) Finally !! The most requested thing will be added, your main character will finally breed the 4 main girls and they will have new positions and they can give offsprings and most likely milk them. (You already can H them but only that in a CG animated scene and only when you max out their likability,) (Dev Note #3 to 6)
5) A new building will probably be added. Seems like only for the main girls since it looks like a bar where you can breed the main girls (Dev Note #6)
Seems like the DLC
Here's the developer ci-en:
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