The film RE-18 MIGHT be featured in either studio JAMS' Ultimate Collection series 8 or 14 (JCD-08 or JCD-14). Unfortunately data on these productions are difficult to come by. I have data on all JCD productions from 1 to 38, apart from 8 and 14, so with some deduction, it's reasonable to assume that RE-18 might be featured in one of those two JCDs.
RE-18 is a film produced by studio Agastia, and is the 18th instalment of the studio's famous Red Eyes series. The production stars a model by the name of Madoka.
Studio Agastia later turned into the studio which is now known as JAMS. Studio JAMS eventually created the "Ultimate Collection" series, commonly referred to as (JCD).
Many of the old studio Agastia productions can be found in the JCD series. Unfortunately, the JCD films appear to be almost as rare as the RE films.
Here are some sources on this production:
Agastia RE-18 Archive - https://web.archive.org/web/20050321032607/http://www.agastia.com/RE/RE18.htm
JAMS JCD-08 or 14 - (unknown)
On a different matter... RE-09 is a production I am eagerly searching for. It's also featured in studio JAMS' Ultimate Collection series 4 (JCD-04). It stars a model known as Kana, Kana Hanashiro, Mistress Kana, Queen Kana, Queen Kana Hanashiro or Glamorous Queen (misspelt as "Glamourous Queen").
Some sources:
Agastia RE-09 Archive - https://web.archive.org/web/20050321033238/http://www.agastia.com/RE/RE09.htm
JAMS JCD-04 - https://www.arzon.jp/item_678825.html
She also features in the following JCDs:
JCD 13 - https://www.arzon.jp/item_480519.html
JCD 15 - https://www.arzon.jp/item_480520.html
JCD 24 - https://www.arzon.jp/item_480529.html
I know there's a 15 minute clip floating around out there, but I'm searching for the full thing, either RE-09 or JCD-04. If you have any info on it, or if you wish to help me search for it, please DM me. It's a great production! Thank you and enjoy.