Even if more difficult than the neighbouring routes such as Amistad con el Diablo o Martínez Somoano, the Cainejo in the East Face in the Urriellu (Naranjo de Bulnes) is one of the most beautiful and recommended on this face. It's been recently restored*, so it's becoming more popular and is repeated more often. A route in the same lines as its companions on the East Face, you'll need to pay attention to the itinerary, exceptional rock quality, anchors in cruxes but distant from each others in the easier sections. Unlike the others, its difficulty is generally more sustained.
Don't mistake the Cainejo route in the East Face of the Urriellu for the Pidal-Cainejo route which is located in the North Face.
The key pitch is the third one. There's an obligatory friction move, but it's protected with a bolt. The fifth pitch is excellent. The sixth pitch is well-equipped and easily "friggable", still, 7a seems a bit excessive to us (at least if you compare it with the rest of the routes of this mountain).
We get back down using the rappels that have been set up in the South Face. Traditionally, people used to rappel down the Directa de los Martínez but two parallel lines have recently been installed to avoid gatherings as well as disturbing people climbing the Directa de los Martínez (see descent description).
*Restoring consists in updating the out-dated anchors of a route. Replacing the spits/burils by stainless steel bolts, checking the pitons, changing the cordelettes and cleaning the choss. No new anchor is added, only the ageing ones are replaced.