Added her 3rd and 4th(half of it-it's all I have) albums. She only did 4 albums. I'll up the singles next - I don't have full singles, but I have quite a few tracks that aren't on the albums.
Her strongest H!P connection that I'm aware of is (TV) Abe Natsumi + Yasuda Kei - Folk Days (2005.09.11) - Tomoe-chan Folk Guerrilla Live in Odaiba.avi - concert she setup that had Abe and Yasuda as guests performing songs solo and together with her.
She's done those Folk concerts every year (always on 8th Aug) for the last 5 years. H!P people have appeared in 2003(Kei,Yuuko,MKB), 2005(Nacchi,Kei), 2006(Nacchi) (I don't have any info about 2002 & 2004).
Here's a clip from Folk Days #2 (Odaiba, 2003.08.08) with Yasuda Kei, Nakazawa Yuuko, Melon Kinenbi, Shimokawa Mikuni
songs: Kemeko no Uta, A no Subarashii Ai wo Mou Ichido