いSo?, Well? (friendly or familiar)

い is a sentence-ending particle in Japanese that will often be seen in compound structures with other particles, or auxiliary verbs. It adds a sense of familiarity and friendliness to the base meaning of what it is being paired with.

い is usually only used by men, when speaking to someone of a lower social position. This social position difference is more in reference to age than anything else, so い being used when an elderly person is speaking to a younger person is very common.

This feeling of familiarity is best conveyed when い is paired with the sentence-ending particle か, or the auxiliary verb だ.

い may also be paired with more emphatic sentence-ending particles such as わ, や, and ぞ, or the auxiliary verb た. However, these combinations are far less common, and won't be seen very often.

Caution

Despite い primarily being used by men, it is not a strict rule, and women do occasionally use it. This is especially true when partnered with either か, だ, or わ.

Caution

Although uncommon, い can also be used with the imperative form of verbs to create a slightly less strict sounding order or command.

Once again, this use is very rare, and will almost never actually be used in real life. It may, however, appear in books.