Seeing Majikoi S in VNDB, the seiyuu for Kawakami Momoyo and Christiane Friedrich is written as Kamishiro Misaki and Misaki Rina respectively. People that is not too into seiyuu might not know, but the seiyuu-otaku are very likely to know that they Kamishiro Misaki is Asawaka Yuu and Misaki Rina is Itou Shizuka. The first is even more easily recognizable by non-seiyuu-otaku and non-anime-otaku since she is the voice provider for the VOCALOID Megurine Luka.
Heck, even people that doesn't know this would be able to find it relatively easily with some Googling. I tried entering the name Kamishiro Misaki in Google and the 5th entry states Asakawa Yuu's name.
Misaki Rina is even worse. It clearly shows that Misaki Rina is Itou Shizuka.
If they are relatively unknown seiyuu, then it can be said that they use such alias so that later when they finally get famous people wouldn't link them to their previous work as eroge seiyuu. But these two are famous seiyuu even during the time Majikoi S was released. Also the Majikoi anime was aired between 2 Oct 2011 and 18 Dec 18 2011, while Majikoi S was released in 27 January 2012. Given that
- those 2 reprise their role in the anime,
- they voiced it the same as when they voice the character in the Visual Novel,
- and that the anime clearly stated that Christiane Friedrich is Itou Shizuka and Kawakami Momoyo is Asakawa Yuu,
it doesn't take a genius to figure that it is them.
This is apparently common in female seiyuus while many male seiyuus use their usual name even when voicing eroge. For example the BL Emperor, Toshiyuki Morikawa, uses his name, Toshiyuki Morikawa in most of his Visual Novel works even if the said work is a R-18+, such as Gin no Kanmuri Ao no Namida.
Most, if not all famous female seiyuus use alias to voice R-18+ games. Examples other than Itou Shizuka and Asakawa Yuu would be Sato Rina, Goto Yuko, all use an alias when doing most of their eroge works.
My question is, since it is clear that it is them, why do most popular female seiyuu still bother using alias when voicing eroge?