Romeo no Aoi Sora, Ie Naki Ko Recommendations
Both stories are bildungsroman tales about young boys who are forced to set out on a character-building journey. The reasons for starting the journeyin both stories are similar but the circumstances of the boys differ slightly. Throughout the journey these boys meet many lovely people and many evil people and are initiated into adulthood through a wide range of joyful and sad experiences.
Both characters found out that they've been adopted. Both get sold in the end to get money (though Romeo decided to sell himself). Also, both anime's are really sad and will make you cry.