Coix lacryma-jobi, universally known as Job’s tears, tear grass, or hato mugi, is a tall, tropical perennial grass in the family Poaceae. It is native to Southeast Asia but has been naturalized across tropical regions worldwide. The genus name Coix is derived from the Greek koix, a name ancient botanists used for a type of palm, while the species epithet lacryma-jobi is Latin for "Job's tears," a vivid reference to the hard, pearly, tear-shaped involucres that enclose the seed. Historically, these uniquely shaped, durable seeds have been utilized not only as a staple grain but also as beads for jewelry and rosaries across various cultures, bridging the gap between subsistence agriculture and ceremonial craft.

The plant is a robust, moisture-loving grass that can grow up to 1–2 meters in height, favoring humid, marshy environments, riverbanks, and wet meadows. It features long, broad, lance-shaped leaves similar to maize and produces small, clustered flower spikes. The most distinctive feature of Coix lacryma-jobi is its fruit, which is encased in a highly calcified, shell-like structure (an involucre) that varies in color from white and grey to dark brown. For culinary use, the outer shell is removed to reveal the edible kernel, which is creamy-white and possesses a texture and mild, nutty flavor reminiscent of barley or brown rice. While wild varieties often have extremely hard shells, domesticated varieties have been selectively bred to possess thinner shells for easier processing.

Job’s tears are a staple cereal crop in many parts of Asia, particularly in East and Southeast Asian cuisines. In traditional Chinese and Japanese gastronomy, the polished grains are prized for their versatility; they are commonly boiled into thick, restorative congees, incorporated into soups to provide a chewy texture, or ground into flour for specialty baked goods. In Korea, a popular beverage called yulmu-cha is prepared from roasted, powdered Job's tears, often mixed with nuts to create a creamy, nourishing drink. Because the grain is naturally gluten-free, it has gained renewed interest in modern global health-food markets as a nutrient-dense alternative to traditional wheat or barley.

Nutritionally, Job’s tears is a powerhouse of complex carbohydrates, dietary fiber, and high-quality plant protein. It is notably rich in essential amino acids, particularly leucine, valine, and isoleucine, which are vital for muscle maintenance and energy metabolism. The grain is also a good source of B-group vitamins, calcium, iron, and phosphorus. In Traditional Chinese Medicine and Ayurveda, it is highly regarded for its "cooling" properties, often prescribed to promote diuresis, reduce inflammation, and support healthy skin. Modern pharmacological research centers on its bioactive compounds, such as coixol (a benzoxazinoid with anti-inflammatory potential) and specific polysaccharides and fatty acids (like palmitic and linoleic acid) that exhibit promising antioxidant and anti-tumor activities.