Rin Isozaki

Given how he is dressed most of the time and that he is introduced while doing housework, Rin is Ran's elder brother and is most likely in high school. Always having thought of Ran as being a little weird, Rin is not surprised to learn of his little sister's supernatural powers and wishes that he had some as well. Rin is the first to draw a preliminary correlation with the mysterious events at the start of the series and will likely become indispensable in the future for this reason considering how he has coached Ran through using her powers and helping to interpret what she learns through that means.
(from Wikipedia)