The keywords "SKYHD" and "UPD" in the search string indicate technical and archival specifications:
: This prefix is used for the series' High Definition releases. While earlier volumes were standard DVD quality, the SKYHD line was designed to take advantage of Blu-ray technology for superior image clarity. sky angel blue vol 43 skyhd 043 upd
The franchise is one of the most prolific in its industry, spanning hundreds of volumes. The keywords "SKYHD" and "UPD" in the search
: The series has featured major stars of the genre, including Maria Ozawa (Vol. 22) and Aya Sakuraba (Vol. 14). sky angel blue vol 43 skyhd 043 upd