Hi, to complete the game, you need to replace the current manager for either Team A or B & that requires you to complete objectives for either Illegal Substance storyline (Team A) or Murder In Office storyline (Team B). You can refer to the checklist screen to keep updated of the progress.
You must join either Team A or B & once you've solved the storyline by removing the manager, there should be option to replace them during department meeting on Tuesday. The secret to get highest work contribution is to only work when healthy to keep within 100% work productivity which means if you get sick or wounded, go to your apartment & sleep at bed to get healthy.
You can also experiment with mood as low mood makes you work longer thus improving work contribution but too low mood makes you unable to finish daily task to get money.