Complex sentence: Then we are introduced to his new identity; he is the most discussed person and the headache of the imperialistic power, the central gem of Saimum which is an organization working for oppressed people and against the imperialistic power.
Split into simpler sentences: Then we are introduced to his new identity; he is the most discussed person and the headache of the imperialistic power, the central gem of Saimum. Saimum is an organization working for oppressed people and against the imperialistic power.