IDK if im doing something wrong? But do you really just can earn one coin per day with libary work? Because for example the bikini buy for nami for 14 coins needs 14 day of work?
After Ash's second event, you can buy improvements for the town from her via phone or the principal's office at the school. You can improve the library or cafe to increase your income per work. You can also improve the dojo for more stat gains during training. And you can improve the school to increase your grades while studying.