Chocotto Sister

due to the story in both series although different they share subplots to some extent 

Both series involves a male protagonist who takes a parenting role in order to take care of a younger girl. In both series, there is a lighthearted mood that details the fun relationship between the duo. Their dialogues varies but shifts from comedic, emotional, and passive many times. Both series' main female protagonists have similar personalities. Both series has comedy, drama, and a little romance in them. 

-Both share the same atmosphere. -Both anime focus on the non romantic relationship between siblings (In Chocotto Sister the little sister is not related by blood to her older brother though) and how characters care for each other. In both anime some of the problmes the characters face are some misunderstandings and sometimes lack of mutual trust. -Both have cute and heartwarming moments. -Both have super cute little sisters. Just keep in mind that Chocotto sister has more fanservice (nothing like To love ru or any other ecchi anime) and may not be as suitable for children as Binbou Shimai.  

Both series are about girls that have been appeared in this world not without the aid of magic. Both heroines are very resilient. Though their life situations are different, they look somehow similar to me. Finals of these series also have some similarities (on my opinion) 

Both These anime have a a single male student living in a cheap apartment who suddenly have to take care of a young girl/girls. The also have in common that both have allot of nice persons around willing to help out with taking care of the girls. In both cases the male students also have to watch there money and end up working allot and in both cases they know someone who helps them get good paying jobs easily. What's more is that both of them have a nice serious story line with a good sense of humour and some sexy misunderstandings. 

Though the relationships are certainly different in the animes, they have a very similar premise. A low-spirited guy has a girl enter his life that brings him happiness.  

Both have a girl learning simple things about life. And the guys that help them. 

Apartament in the city... Crazy people in it...