Convallaria, a poisonous, woodland-native, flowering plant native to cool temperate climates in North America, Europe, and Asia. Its Japanese name is 鈴蘭 / スズラン (suzuran) and its Chinese name is 鈴蘭 / 铃兰 (Linglan).
The flowers come in clusters, dangling from curved, alternating offshoots from a main stem (aka raceme) and are bell-shaped and (usually) white. All parts of the plant are poisonous, including its red berries.
They bear a strong resemblance to snowbells, however they're different species. Major visual points to notice: the snowbells have green or yellow marks on a tip of each petal; each flower stalk ends with a "bulb" (receptacle) upon which a flower is attached. A good visual example is post #2894988 with snowbells to the left and lilies of the valley to the right.
Also, not to be confused with bellflower whose flowers typically have a longer, less rounded bell shape.