What type of government was established in Manipur after the elections of June 1948?

Constitutional Monarchy.

Manipur was a princely state with its own monarch, Maharaja Bodhchandra Singh, and a distinct political and administrative system.
It enjoyed a measure of autonomy under British colonial rule.
Maharaja Bodhachandra Singh of Manipur signed the Instrument of Accession with the Indian government shortly before Independence.
The agreement ensured that Manipur would maintain its internal autonomy.
In response to public opinion, elections were held in Manipur in June 1948, establishing a constitutional monarchy.
Manipur became the first part of India to hold elections based on a 'universal adult franchise'.