From an old interview with hiroki Hayashi. The co-producer of OVA 1.
H: uh...as everybody knows that Mr. Kajishima came to AIC for he likes Kenichi Sonoda's "Gall Force" very much and it's the biggest reason he joined AIC many years ago. We knew each other through "Gall Force".
J: And came up the idea of "Tenchi" while working on "Gall Force"?
H: No. It's not from there. We also work together on episode 4 of "Bubble Gum Crisis-". We came up "Tenchi" idea while we were working on "B.G.C".
J: "B.G.C" is where "Tenchi" world came from?
H: In certain sense it is. "Bubble Gum Crisis" is a pretty gloomy anime. Serious fighting, complicated human relationships, and dark Mega Tokyo. Kajishima and me just thought it will be fun to put some comedy portions in "B.G.C", like, girls WITHOUT Knight-Saber suits go to hot spring tour, and Boomer show up suddenly while they are taking a bath in hot spring bathtub with no cloths on...something like that. We brought the comedy edition "B.G.C" project to sponsors but we were "politely and kindly" rejected. 10 something years ago, it's sort of the "trend" that bunch of female characters or bunches of male characters with one female character, just like "Gall Force", "Bubble Gum Crisis" and many classic robot anime. We were working in that "trend" and asked ourselves: "What about Macky (-Syria's brother in Bubble Gum Crisis)? What is his story?" We thought it would be interesting to use a Macky as a main character and make a reverse version "Bubble Gum Crisis". That thought was the trigger for us to start writing "Tenchi" story. Fortunately, we got budget this time to make 6 episodes and that is how "Tenchi Muyo! Ryohki" OVA series started.
----------
Episode 4 of the tenchi ova is in fact a re skinned episode of bubblegum crisis. and oddly so. if you are a fan of both series like i am once you know this fact you can't unsee it every time you watch. its so obvious.
in my opinion these are the substitutions
the lion alien in the beginning is the black police chief
Mihoshi is nene
Ryoko is priss
Tenchi is Makie
Sasami is Sylia
Ayeka is lene
the ghost ryoko summons is a boomer that shows up ruining their onsen visit.
its a nene joins the nightsabers story
I love ryoko and i love priss so this just makes ryoko 10 times better in my opinion.
Mihoshi is nene
Ryoko is priss
Tenchi is Makie
Sasami is Sylia
Ayeka is lene
the ghost ryoko summons is a boomer that shows up ruining their onsen visit.
its a nene joins the nightsabers story
I love ryoko and i love priss so this just makes ryoko 10 times better in my opinion.