Comprehension of this will most likely require having recently read "Ouji-sama Game," "Ou-sama Game," and "Kaizoku Game" by Takagi Ryo.
There seems be confusion over Rien's existence, his relationship with Yuuri, and Yuuri's location. I'll refer to the kingdoms as the kingdom of 7 princes (k7p - crown prince Ryuuen) and the kingdom of 6 princes (k6p - king Ouga).
At the beginning of "Ou-sama Game," the kingdoms trade one prince to the other kingdom as a show of alliance. Yuuri of k6p was traded to k7p, so Rien is the 4th prince from k7p. Yuuri's having been traded is supported by the fact that all k6p princes, with the exception of Yuuri, are seen in their home kingdom during Renge's search for his mysterious night suitor. Also, Yuuri is being watched over by guards of k7p (such as the 4th gun squad leader Suzaku), which places Yuuri as having been in k7p. We later see k6p 2nd prince Mizuchi aboard the pirate ship because Kuuron was probably secretly taking Yuuri home to k6p. Mizuchi takes advantage of the pirate ship's being in k6p waters and launches an attack on Kuuron's crew.
As to why Rien refers to Yuuri as his brother/family and vice versa, it's more a show of their deep relationship than any actual blood relation. (Takagi Ryo must have slipped in the Japanese social custom of referring to strangers in familial terms.) Rien was poisoned after the prince trade occurred and thus became distrustful of many people. Despite not being blood-related, Rien recognized Yuuri's sweet personality and nature, and Rien trusted Yuuri to not poison him. Rien also began to believe he loved Yuuri.
To tally this up, k7p: - 1st prince Ryuuen & assassin Seiran who becomes royal consort - 2nd prince Renge (traded) & king Ouga - 4th prince Rien & pirate cook Kougyoku - 6th prince Kagetsu & tactician Jin (though squad leader Suzaku likes Jin) - 7th prince Shuki (is closest to 2nd prince and thus goes to k7p to bring him back) & tutor-turned-slave Fuanron
And k6p: - 1st prince (king) Ouga & k7p 2nd prince Renge - 2nd prince Mizuchi (usurpation plot - fate unknown) - 3rd prince Homura & 6th prince Airi - 4th prince Ryuuga (narcissistic playboy) - 5th prince Yuuri (traded) & pirate captain Kuuron - 6th Prince Airi & 3rd prince Homura
I'm not certain if this confusion was due to a plot mix-up on the author's part - I'll have to look at the raws - but I'm more inclined to believe that these subtle details were lost in translation.
(As an extra side note, according to the untranslated author's afterword of "Ouji-sama Game," Ryuuen is bisexual and we've yet to see the 3rd and 5th princes so there is hope yet for k7p's continued lineage. On the flip side, k6p is probably doomed.)
(Well, we also don't know about either kingdom's princesses - the story's numbering system was only for the princes. But k6p is still probably doomed.)
Comprehension of this will most likely require having recently read "Ouji-sama Game," "Ou-sama Game," and "Kaizoku Game" by Takagi Ryo.
There seems be confusion over Rien's existence, his relationship with Yuuri, and Yuuri's location. I'll refer to the kingdoms as the kingdom of 7 princes (k7p - crown prince Ryuuen) and the kingdom of 6 princes (k6p - king Ouga).
At the beginning of "Ou-sama Game," the kingdoms trade one prince to the other kingdom as a show of alliance. Yuuri of k6p was traded to k7p, so Rien is the 4th prince from k7p. Yuuri's having been traded is supported by the fact that all k6p princes, with the exception of Yuuri, are seen in their home kingdom during Renge's search for his mysterious night suitor. Also, Yuuri is being watched over by guards of k7p (such as the 4th gun squad leader Suzaku), which places Yuuri as having been in k7p. We later see k6p 2nd prince Mizuchi aboard the pirate ship because Kuuron was probably secretly taking Yuuri home to k6p. Mizuchi takes advantage of the pirate ship's being in k6p waters and launches an attack on Kuuron's crew.
As to why Rien refers to Yuuri as his brother/family and vice versa, it's more a show of their deep relationship than any actual blood relation. (Takagi Ryo must have slipped in the Japanese social custom of referring to strangers in familial terms.) Rien was poisoned after the prince trade occurred and thus became distrustful of many people. Despite not being blood-related, Rien recognized Yuuri's sweet personality and nature, and Rien trusted Yuuri to not poison him. Rien also began to believe he loved Yuuri.
To tally this up, k7p:
- 1st prince Ryuuen & assassin Seiran who becomes royal consort
- 2nd prince Renge (traded) & king Ouga
- 4th prince Rien & pirate cook Kougyoku
- 6th prince Kagetsu & tactician Jin (though squad leader Suzaku likes Jin)
- 7th prince Shuki (is closest to 2nd prince and thus goes to k7p to bring him back) & tutor-turned-slave Fuanron
And k6p:
- 1st prince (king) Ouga & k7p 2nd prince Renge
- 2nd prince Mizuchi (usurpation plot - fate unknown)
- 3rd prince Homura & 6th prince Airi
- 4th prince Ryuuga (narcissistic playboy)
- 5th prince Yuuri (traded) & pirate captain Kuuron
- 6th Prince Airi & 3rd prince Homura
I'm not certain if this confusion was due to a plot mix-up on the author's part - I'll have to look at the raws - but I'm more inclined to believe that these subtle details were lost in translation.
(As an extra side note, according to the untranslated author's afterword of "Ouji-sama Game," Ryuuen is bisexual and we've yet to see the 3rd and 5th princes so there is hope yet for k7p's continued lineage. On the flip side, k6p is probably doomed.)
(Well, we also don't know about either kingdom's princesses - the story's numbering system was only for the princes. But k6p is still probably doomed.)