A conservative group in Japan's ruling party on Wednesday finalized a proposal to allow men from previously severed collateral branches of the imperial family to rejoin it in order to ensure stable male succession.

The proposals, to be submitted to Prime Minister Shinzo Abe, were crafted as the number of successors to the Chrysanthemum Throne dwindles.

The 1947 Imperial Household Law stipulates that only males in the family's male line can ascend to the throne. Following the enthronement of Emperor Naruhito, the family now has only three such heirs: the emperor's younger brother, Crown Prince Akishino, 53; the crown prince's son, Prince Hisahito, 13; and Prince Hitachi, the emperor's 83-year-old uncle.

To sustain the imperial family, the Liberal Democratic Party group came up with ideas such as letting unmarried men in the former branches marry into or be adopted by the family.

The group has suggested creating a law on this as an emergency measure, instead of revising the Imperial Household Law.

The emperor has a daughter — Princess Aiko, 17 — and there are other females in the family, but the Imperial Household Law requires women to abandon their imperial status after marrying commoners.

The group opposes allowing women to remain imperial family members after marriage.

The proposals came after 59-year-old Emperor Naruhito proclaimed his enthronement on Tuesday before some 2,000 guests, including dignitaries from about 190 countries and international organizations.

He became Japan's 126th emperor on May 1, the day after his father, now Emperor Emeritus Akihito, stepped down — the first emperor to do so in 200 years.