Oji-Po + Oji-Run + Oji-Help

If you do everything thoroughly, you can earn about 150 yen a day. In reality, it takes too much time to do that, so it's a bit iffy, but if you do Oji-Run a moderate number of times while watching the 2x dash ads, you can reach about 50 yen a day in a reasonable amount of time. Both Run and Help rewards have been nerfed since the beginning, but I think Run is still pretty good. When you complete 100 runs, the clear reward drops to 2, so it's better to do Help rather than just continuing Run.