At the start of 2015, Mexican national Horacio Hernandez Herrera, allegedly third in command of the infamous Sinaloa Cartel, was arrested in the Philippines' capital, Manila, at the center of a 12 million peso ($255,000) drug bust.

Herrera's arrest came as Philippine authorities confirmed that not only were Mexico's cartels vying for a piece of the country's rapidly growing drugs trade, but forming an alliance with Chinese syndicates to do so.

The Philippines drug of choice? Shabu: A local name for crystal meth, present in over 90 percent of the capital's neighborhoods.

While shabu's popularity has skyrocketed in the last decade — partly for its ability to allow the poorest of Filipinos to work longer hours — the drug's grip on Manila has reached crisis point, as unemployment rates remain high and the collusion of gangs with police and local government becomes an every day occurrence.