The Monarchies

Rainbowisland is the last remaining true Empire on the planet. It consists of 8 kingdoms, each headed by a monarch. The country as a whole is headed by the Emperor.
The title of Emperor is not hereditary. In stead, the people (every person of age 18 or older and legally competent) choose who their Emperor will be. They can choose between the 7 kings of Rainbowisland. These are the kings of Crawrealm, Gaalirealm, Puipilrealm, Southrealm, Kastelia, Kastelland and Forria and the Eastsea. Montana is an exception. Because Montana has a certain degree of independance, its king can not be elected as Emperor. Of course, there is an exception to the exception. In times of war, the king of Montana CAN be elected as Emperor. If this happens, the king of Montana becomes Emprial Regent (while keeping his title of King of Montana) and at the end of the war, he (or she) gets to decide whether to keep his title or to vacate the throne. (This has happened twice and both times, the Emperial Regent vacated the throne)
When one of the regular candidates is elected as Emperor, his title of King is replaced by Emperor, even for his own kingdom.

The current Emperor is Loran XXV of the Forrest. He was elected on the 12th of july 1974, 45 days after the death of Emperor Vercingetorix CXXI of the Rainbowisland. He was King of Forria and the Eastsea at the time.
The way the successors to the various kings are chosen is different for all 8 kingdoms. Here is some information on the various kingdoms:

Crawrealm

The monarch of Crawrealm is refferd to as "of Craw". The current monarch is King Arn I of Craw. He became king upon the death of his mother Queen Carolin VI of Craw.
In Crawrealm, the monarch is the oldest child (or in the absence of children, the oldest sibling) of the previous monarch. The throne of Crawrealm is therefor open to both men and women.
As an aditional note, every year, there is a referandum. If the people vote against the monarch, he looses his title for one year (and is not replaced during that year). The government has to order the referandum and almost always "forgets" to do this.

Gaalirealm

The monarch of Gaalirealm is refferd to as "of Gaul". The French government has objected to this. The problem was resolved when Gaalirealm explicitly added to its constitution that it had no rights whatsoever to any part of ancient Gaul.
The current monarch is Prins Regent Charles LXI of Gaul. The title "king" is not actually used, due to a very confusing period in the middle ages. Charles LXI became regent when his brother Louis LII died in an accident. (Louis LII only had daughters). His ascention was approved by the regional government. (If the government hadn't approved it, Gaalirealm would be without head of state until Charles LXI had died)
In Gaalirealm, the monarch is the oldest son (or in the absence of sons, the oldest brother) of the previous monarch. The throne of Gaalirealm is not open to women.

Puipilrealm

The monarch of Puipilrealm is refferd to as "of the People". The current monarch is King Robrecht XI of the People. He became king upon the death of his aunt Queen Machteld VII of the People.
In Puipilrealm, the monarch is the oldest child (or in the absence of children, the oldest sibling) of the previous monarch. The throne of Puipilrealm is therefor open to both men and women.

Kastelland

The monarch of Kastelland is refferd to as "of the Castle". The current monarch is King Beowulf XIII of the Castle. He was elected king upon the death of his father King Hamlet II. (it is very rare for the crown to stay in the same family for more than 1 generation)
In Kastelland, the monarch is choosen by the local nobles from amongst the local nobility. All noblemen (and women) are candidates, which includes recipients of the Medal of Rainbow (which makes them non-hereditary nobles).The throne of Kastelland is therefor open to both men and women.

Forria and the Eastsea

The monarch of Forria and the Eastsea is refferd to as "of the Forrest". The current monarch is Emperor Loran XXV of the Forrest. He became King upon the abdication of his grandfather King Robin I of the Forrest. Robin I was 83 at the time and felt it was time for fresh blood. Crownprins Robin (father of Loran XXV) refused the throne for the same reasons. Only 3 years later, Loran XXV was elected Emperor.
In Forria and the Eastsea, the monarch is the oldest child (or in the absence of children, the oldest sibling) of the previous monarch. The throne of Forria and the Eastsea is therefor open to both men and women.
As an aditional note, the government can call for a referendum. If the people decide against the monarch, he is forced to abdicate (King Robin I abdicated out of his own free will). Such a referendum can only be called once every 6 years.

Southrealm

The monarch of Southrealm is refferd to as "of the South". The current monarch is King Filipus XIV of the South. He became King upon the death of King Gorrix XLII of the South.
In Southrealm, the monarch is elected by the people from amongst the local nobility. All noblemen (and women) are candidates, which includes recipients of the Medal of Rainbow (which makes them non-hereditary nobles). The throne of Southrealm is open to both men and women.

Kastelia

The monarch of Kastelia is refferd to as "of the Rainbowisland". The current Monarch is King Vercingetorix CXXII of the Rainbowisland. He was elected King upon the death of his father Emperor Vercingetorix CXXI of the Rainbowisland.
In Kastelia, the monarch is choosen by the people from amongst the sons (or in the absence of sons, the brothers) of the previous monarch. The throne of Kastelia is therefore not open to women.

Montana

The monarch of Montana is refferd to as "of the Mountains". The current monarch is King William XXIII of the Mountains. He became king upon the death of his father King Albert III of the Mountains. Due to King Williams young age (he was born in 1984), the position of head of state (and head of government) goes to King Williams Uncle, Prins Regent Pieter.
In Montana, the monarch is the oldest child (or in the absence of children, the oldest sibling) of the previous monarch. The throne of Montana is therefor open to both men and women.
As an aditional note, the monarch of Montana is not only head of state  (like all of the other monarchs) but also head of his regional government.