Stargazing: Zutto - Tomohisa Sako
Slow-paced is a word used by a few of my friends when they describe Kimi to Boku. While I have not seen the series myself, I have checked out the opening theme to its second season.
Tomohisa Sako is someone I have run across a few times in the anime world. His lightweight music is always catchy and memorable, and it just adds a sense of delight to a series if utilized properly. It's perfect for fun shows that incorporate a bit of wholesomeness emotion to them, and 'Zutto' is a testament to that.