Major streaming platforms do not host "R18+" (hardcore) content. Kuroinu is not ecchi (mild fanservice); it is hentai (explicit adult animation). Therefore, it lives exclusively in the adult ecosystem.
To answer "where is EP 3 exclusive," we must first clarify what "Episode 3" means in this context. The Kuroinu anime is not a standard seasonal TV series. It is a series of OVAs released on DVD and Blu-ray. Major streaming platforms do not host "R18+" (hardcore)
As of late 2024, the situation is improving. The adult entertainment industry has seen a shift towards "westernization" of Japanese hentai. To answer "where is EP 3 exclusive," we
The Visual Novel Remaster: In 2023, Kuroinu Redux (an uncensored version of the original game) was released on Steam and GOG. The sales were massive. This proved there is a western appetite for Kuroinu. As of late 2024, the situation is improving
The Prediction: The publisher Shiravune (who released the game) is likely to partner with a hentai OVA distributor (like Critical Mass Video or Adult Source Media) to release a Kuroinu OVA Complete Box Set including Episodes 1-4, uncensored, dubbed. If this happens, "Kuroinu Episode 3 Exclusive" will finally be on Amazon US, RightStuf (now Crunchyroll Store), and maybe even Steam.
Until then, the "exclusive" remains a premium item buried in the deep web of Japanese adult retailers and the preservation archives of hentai torrent communities.
If you have searched Crunchyroll, Funimation, Hulu, or Netflix, you came up empty. Here is why.