Ryuuren Ran

The youngest of the five brothers of the Ran family. He is eighteen years old. It is said that, out of his four older brothers he was the most worthy of the name Ryuuren Ran because he is a genius. He calls his older brothers foolish and doesn't call them by their name, rather: Shuuei = "foolish elder brother the fourth". Recently, he's called Shuurei, Soul Friend #1, and Eigetsu, Soul Friend #2 (He refers to Yougetsu as Soul Friend #2.5).

He does things on his own time and is quite impulsive: when he was going to buy ingredients for chicken stew with Shuurei, he ended up buying soy beans, then he traded that for boiled eggs, then traded the eggs for spring onions, then the spring onions for wood blocks, then flowers, then fish, then straw, and then he gave away the straw to a little girl and just ended up with one stalk of straw. Later in the series, he goes ghost hunting after hearing about a late-night ghost. He also pulls out his flute and plays it without warning, often off key. Since he can't be easily told what to do and is very unpredictable, he's necessary in the Ran family.

Although, because of this behavior many find him weird and annoying, so they usually distance themselves from him. Shuurei was the only one who put up with him, so he said that she's now his soul friend. Also according to Kurou he is also a candidate for Shuurei's political marriage. (Source: Wikipedia)