Every year, Nepalis from all walks of life pay homage to a red-faced idol nestled in a 32-feet tall chariot of wood and vine. The wobbly-looking chariot, weighing several tonnes, would be pulled by dozens of men and women through the narrow streets of Katmandu, for all to revere and worship.

The month-long festival begins with the construction of the chariot – made from wood, cane and rope, and without a single nail – a testament of the ingenuity of Newari architecture. Known as Rakhamiyas, this special group of Newaris are tasked with the same mission every year – to build the chariot within 15 days of the date foretold by priests. The chariot – literally a temple on 5-feet-wide wheels – would make its way to several landmarks in Katmandu, where devotees would flock around to offer gifts and light butter lamps.

As devotees pray in earnest and reverently touch their heads of the hulking chariot, Lord Rato Machhindranath, harbinger of the monsoon, looks impassionately ahead. Locals believe that this Buddhist deity brings ample rains and abundant harvests – a very important role for a society where 70 percent of its people still depend on farming for livelihood.

The Rato Machhindranath ends with the Bhoto Jatra, the unveiling of a black diamond-studded vest, believed to be a personal possession of the red-faced god himself. Although the original vest is rumoured to have found its way into a foreign museum, thousands of continue to turn up, year after year, to witness the event, and to honour the harbinger of the monsoon.

For what is summer without the rain? And what harvests would there be if the rain fails to come on time?

Left: As the 32-feet tall chariot is paraded along the narrow streets of Kathmandu, helpers climb to rooftops to right the chariot's angle with ropes, to avoid smashing the fragile steeple against street lamps and buildings.

Photographer: Edwin Koo

The Coconut Jatra is one of the quirky portions of the month-long festival, when a coconut is dropped from the top of the towering steeple to the waiting crowd eager to catch up. It is believed that the person who grabs it will be blessed with a son.

Photographer: Edwin Koo

A devotee touches her head to the ancient bronze mask of the Bhairab - a powerful Hindu deity - hung at the front of the chariot.

Photographer: Edwin Koo

Machhindranath, the rain god is a strangely childlike figure made of roughly carved wood, with his face painted bright red.

Photographer: Edwin Koo

An old man would tease the crowd with the coconut many times, before he finally drops it.

Photographer: Edwin Koo

Built from 16 different kinds of wood and cane rope, the chariot is crafted by the Rakhamiya craftsmen from the Newari community, with knowledge passed down the generations exclusive to the group.

Photographer: Edwin Koo

Both Hindus and Buddhists alike celebrate the festival of Rato Machhindranath, in hope that their devotion would bring about prosperity.

Photographer: Edwin Koo

A devotee lays offerings at the foot of the massive chariot wheel, which carries the eyes of the all-seeing Hindu deity Bhairab.

Photographer: Edwin Koo

A young man celebrates his triumph after grabbing the coconut during the Coconut festival , part of the month-long Rato Machhidranath.

Photographer: Edwin Koo

Devotees raise their hands to catch the falling rice grains, strewn from the chariot of the red-faced deity. In the agrarian society of Nepal, the monsoon is very important for the summer rice harvests.

Photographer: Edwin Koo

In the early hours of dawn, the day after the Coconut festival, women jostle for the rope leading the chariot, believing that a tug at the massive chariot would bring good luck.

Photographer: Edwin Koo

As women jostle for the rope to tug the chariot, many lose their footwear in the frenzy and confusion.

Photographer: Edwin Koo

Patan's Kumari, or Living Goddess witnesses the final day of the Rato Machhindranath festival as a guest of honour.

Photographer: Edwin Koo

The Rato Machhindranath festival concludes with the unveiling of the deity's sacred diamond-studded vest, its origin steeped in folklore.

Photographer: Edwin Koo

After the unveiling of the diamond-studded vest at the final ritual of Bhoto Jatra, Lord Machhindranath is escorted to the village of Bungmati in southern Kathmandu where he will spend the next 6 months before returning to his temple in Patan.

Photographer: Edwin Koo