You don't want to. You can get all the money you'll ever need by working and getting many salary raises, and then just use that same money over and over again on New Game +.
Start a character with no intention of of getting a harem started. Pick a single (as in one) girl to marry. Build up her story slowly while going to work two or three times a day.
Mon to Sat (Sunday is for cleaning and leveling skills slowly)
6 AM wake up, Shower
7 AM breakfast
8 AM work
12 run around the map complimenting girls until you max fun
12 Work
4 PM phone chat and text to max fun
4 PM eat hot dog at mall
4 PM DO NOT drink coffee in the break room.
Why? No Aletta means no office party, means no getting fired if you have low knowledge
4 PM coffee at HOME!
4 PM work
8 PM Dinner
9 PM Shower
10 PM Bed or one fun thing or one skill thing
After four months ( on year in this game) you'll have about two million dollars. You can't actually spend all that money without spamming wedding ring purchases so you're set and don't have to work at all in your next reincarnation. New Game + for the win.