It seems- without me having hammered out a full translation, but just by skimming- to be about a boy named Lagu/Ragu, whose goal is to become a tegamibachi- a "letter bee", or someone whose purpose is to deliver important mail. Hereafter, I'm calling him Lagu, because Ragu reminds me of pasta. >_> In any case, when he was quite young, he was befriended by one of the tegamibachi and he was so down upon his luck and so grateful for the attention and help that he wanted to do the same when he got older.
This backstory takes up most of the first volume, but toward the end is several years later, when he meets a young girl named Nicchi who's being kept prisoner; she is not human, and presumed dangerous. At first, he takes on the task of delivering her as a "package" as he's asked- but in the end, they give the people who'd kept her there their just desserts and take to traveling together. In the second volume, he and Nicchi go about attempting to make sure a particularly important letter gets where it needs to be.
Since it's a Jump series, there's of course weird magic and monsters and lots of action in addition to the pretty art. ^_^
I can share pictures, but I haven't got a scanner so I can't provide raws. >:
Volume one cover.
Volume two cover.
Lagu is saved in the first volume by his role model.
But he grows up to be pretty cool in his own right.
Later, Nicchi finally gives Lagu her name.
And finally, Nicchi watches the memories of Lagu's (angsty) childhood.