Minami Kuramitsu is from the planet Seniwa, the son of Mikumo Kuramitsu and Miyuki, the brother of Mikami Kuramitsu, the father of Mitoto, the grandfather of Mihoshi and Misao, as well as the grandson of Washu Hakubi. Through the course of the series he has served as the Grand Marshall of the Galaxy Police, demoted to the Head of Ship Maintenance, President of the Seniwa Men's Elders Association and named heir apparent as the next Head of the Kuramitsu Family.
The Kuramitsu family is one of the most powerful families on the planet Seniwa, and is the dominant force in the Galaxy Police and Galaxy Army. During the main timeline, Minami is the second child of the Head of the family and De Facto ruler of the Seniwa Empire, Mikumo Kuramitsu.
Minami first appeared in the first OVA series briefly, where he reported to the GP commander that the criminal Kagato had returned. After that the commander found the only officer close by is the Marshall's granddaughter Mihoshi, much to his dismay. Her superior officer Nobeyama then tried unsuccessfully to tell her to not to engage Kagato, to avoid the Marshall's wrath if he were to find out that Mihoshi were in danger.
In the third OVA series it is shown that since Minami loves his granddaughter greatly, so much so that when he received a letter (altered by Z), saying that she was being abused by Tenchi, Minami quickly dispatched her younger brother Misao aboard the Choubimaru, a huge ship owned by the Kuramitsu family, to rescue Mihoshi, and destroy the Earth to kill Tenchi. Minami went through with this plan, despite a warning from the military officer Nakita, that since the Earth is an undeveloped world, he would risk having the Earthlings see it. Nakita also delivered a message from Minami's sister Mikami, that she will sell one of his gardening planets to Lady Seto should the Choubimaru be damaged in the attack, much to Minami's dismay.
In the final episode of the third OVA series, during the meeting to pass judgement on those involved in the Choubimaru incident, by Mikami's judgement, Minami is demoted to the position of the head of maintenance at the G.P. spaceship dock as his punishment. When Misao had decided to marry his assistant Mashisu, at first Minami protested that she was unworthy of marrying into the Kuramitsu family, but was shocked when Mitoto had announced her support and that she was able to get the family council’s approval for the wedding.
Minami has also made a few cameo appearances in Tenchi Muyo! GXP where he not only welcomed Seina to the Galaxy Police, but he and his maintenance crew had also serviced Seina's ship the Kamidake a few times.
Late in the GXP novels, Mikumo Kuramitsu is on his apparent deathbed without having named a successor to the Head of the Kuramitsu Family. When the family is called together for an announcement, Washu arrives and announces that she is Mikumo's mother (a fact that was not widely known), that Mikumo has died and she will read his will. The usual procedure is to name the new head of the family but also name a proxy until the family can decide the next leader is ready to take responsibly. The current President of the Men's Elders Association, Taima Kuramitsu, expects to be named either the leader or the proxy. Instead, Washu announces that Minami will be the next head and Taima's position is to be vacated.  Confusingly, Minami is also later named President of the Men's Elder Association (when Taima is forced to retire from all duties). This seems to mean that he is the Heir Apparent to be the Next Head, but until the full family can agree when he is to be formally named as such, he will hold the next highest men's position, along with his sister, Mikami, the President of the Women's Elders Association. 
- True Tenchi Muyo! GXP Volume 11, Chapter 1
- True Tenchi Muyo! GXP Volume 13, Chapter 8