歳 (sai), or "years" in English, is a term used in Japan to denote age. It signifies the number of years a person has lived since birth. In Japanese culture, age is an important aspect of social interaction, influencing how individuals address each other and their roles within various social settings. For instance, age determines the use of honorifics in language, with older individuals often being addressed more formally out of respect.

In formal and informal contexts, people commonly ask and share their age using the term 歳. For example, a person might say, "私は25歳です" (Watashi wa ni-ju-go sai desu), meaning "I am 25 years old." The character sai is also used in official documents, school records, and legal contexts to record and verify age.

縁の下の力持ち (en no shita no chikara mochi) is a Japanese idiom that refers to someone who works hard behind the scenes, providing essential support and making significant contributions without seeking recognition or praise. This phrase emphasizes the importance of those who play crucial but often invisible roles in ensuring the success and smooth functioning of a group, organization, or project.

In any setting, be it a workplace, family, or community, the en no shita no chikara mochi are the individuals whose efforts may go unnoticed but are vital for achieving overall goals. They are the backbone, often taking on challenging tasks and responsibilities to support others.

下戸 (geko) is a Japanese term that refers to a person who cannot drink alcohol or who has a low tolerance for alcohol. In Japanese culture, it is often used to describe someone who either abstains from drinking or gets intoxicated easily with small amounts of alcohol. The term is commonly used in social contexts, particularly when discussing drinking habits or when someone declines an alcoholic beverage.

前提 (zentei) is a Japanese term that means "premise" or "assumption." It refers to a condition or a basis that is assumed to be true and upon which further reasoning, arguments, or actions are based.

For example, in a discussion or argument, zentei would be the underlying assumption that both parties accept as true before proceeding with their main points. In a business context, it might refer to the fundamental assumptions made when planning a strategy or making a decision.

要介護2 (yokaigo ni) is a classification within Japan's Long-Term Care Insurance system. It indicates a level of need for care and support for elderly individuals. This system, managed by the Ministry of Health, Labour, and Welfare, categorizes care levels from 要介護1 (lowest) to 要介護5 (highest).

Yokaigo ni specifically indicates that the individual requires moderate assistance with daily activities. This includes help with personal care tasks such as bathing, dressing, and eating, as well as support with mobility and housework. The classification is determined through an assessment process that evaluates the individual's physical and mental condition.

Receiving a yokaigo ni classification qualifies the individual for various support services, including home care, day care, and nursing home services. The goal is to provide the necessary assistance to help the individual maintain as much independence as possible while ensuring their safety and well-being.

平均余命 (heikin yomei) refers to "life expectancy" in Japanese. It is a statistical measure that estimates the average number of years a person can expect to live based on current age and mortality rates.

Life expectancy is typically calculated at birth, but it can also be computed for other ages. It reflects the overall health and longevity of a population and is influenced by factors such as healthcare, living conditions, and lifestyle.

In a broader sense, heikin yomei is used in demographic studies, public health planning, and policy-making to understand and improve population health outcomes.