Bishounen no Oheya (Bishounen's Rooms) by Haruko Kurumatani 6 chapters-complete
Koyuko applies to a prestigious school with the intent of marrying a rich guy. She also becomes a maid to "three kings" to pay off debts. It's not really a reverse harem. It's a smutty story of guy being pervy. It's an earlier work of mangaka who brought Gokujou Danshi to Kurashi Temasu and Akutou Danshi Collection . Thanks too to Ei inzali for the tip.