"muyo" means, essentially, "no need for" in Japanese,
so you'll sometimes see this series called "No need for Tenchi!"
The original series of Tenchi Muyo is called the "OAV". There
are 13 episodes in the OAV:
Muyo - OAV DVD Boxed Set" (Pioneer) contains the 13 episodes,
plus a bonus disk, for about $110.