Because

から

kara

(by or for the cause that; on this account that; for the reason that)

ために

(by or for the cause that; on this account that; for the reason that)

だって

datte

(by or for the cause that; on this account that; for the reason that)

なぜなら

nazenara

(by or for the cause that; on this account that; for the reason that)

ので

node

(by or for the cause that; on this account that; for the reason that)

どうしても

dōshitemo

(word used in place of an answer to "why")