Farewell, Kokoro-chan. Long Goodbye Forever and Ever... - S0.E1

After some pushing by Irene and her father and a lack of support otherwise, Kokoro stubbornly quits her job as a police detective to become an idol. She soon finds the idol life draining and starts to miss her old detective life. When Henriette notices Sherlock's loneliness without her, she stages a statue theft in order to convince Kokoro to return to the force.