faction_demand_regent_transfer_effect

faction_demand_regent_transfer_effect = {
	top_liege = {
		save_temporary_scope_as = old_regent_temp
		primary_title = {
			save_temporary_scope_as = primary_title_temp
			title_capital_county = { save_temporary_scope_as = preferred_capital_temp }
		}
	}
	$NEW_REGENT$ = {
		save_temporary_scope_as = new_regent_temp
		if = {
			limit = { government_has_flag = government_is_japan_feudal }
			save_temporary_scope_as = japan_feudal
		}
	}
	# COUNTIES
	create_title_and_vassal_change = {
		type = $REASON$
		save_scope_as = title_change
		add_claim_on_loss = no
	}
	scope:old_regent_temp = { # Give landed titles to the new Regent
		show_as_tooltip = {
			primary_title = { # Give top liege title to the new Regent
				change_title_holder_include_vassals = {
					holder = scope:new_regent_temp
					change = scope:title_change
				}
			}
		}
		hidden_effect = {
			every_held_title = {
				limit = {
					tier > tier_barony # we don't want to try and pass off baronies
					is_landless_type_title = no
					is_noble_family_title = no
					NOT = { exists = var:ceremonial_title } # we don't want to hand away the ceremonial throne, which is not landless
				}
				change_title_holder_include_vassals = {
					holder = scope:new_regent_temp
					change = scope:title_change
				}
			}
			change_liege = {
				liege = scope:new_regent_temp
				change = scope:title_change
			}
		}
	}
	resolve_title_and_vassal_change = scope:title_change
	scope:new_regent_temp = {
		if = {
			limit = {
				has_title = scope:preferred_capital_temp # do I own the preferred capital?
				capital_county != scope:preferred_capital_temp # and is my capital not the preferred capital?
			}
			set_realm_capital = scope:preferred_capital_temp # now my capital is the preferred capital
		}
		# GOVERNMENT
		if = {
			limit = {
				exists = scope:japan_feudal
				NOT = { government_has_flag = government_is_japan_feudal }
			}
			change_government = japan_feudal_government
		}
	}
}

As written in game/common/scripted_effects/10_dlc_tgp_japan_scripted_effects.txt.