Because Nakajima is always that way (i.e., comes late), he will probably come late again today. (literally: Because it is a matter of Nakajima (who habitually comes late)).
(ksb).
傷みやすい豆腐のことだから、冷蔵庫に入れておいた方がいいですよ。
Because tofu goes bad quickly, you'd better put it in the refrigerator. (literally: Because it is a matter of tofu, which always goes bad quickly . . .)
(a).
夏のことだから、食べ物には十分気を付けて下さい。
Because it is summer (when foods go bad quickly), please be very careful about what you eat.
(b).
お金持ちの日本人のことだから、きっと高くても買いますよ。
Because they are rich Japanese, I'm sure they will buy them even if they are expensive.
(c).
カラオケの好きな木下さんのことがから、歌い始めたらマイクを離さないんじゃありませんか。
Because Kinoshita loves karaoke, I have a feeling that he will not let go of the microphone once he starts singing.
(d).
酒好きの山田のことだから、この酒を見たら飲まずには帰らないだろう。
Because Yamada is a sake lover, if he sees this sake, he will probably not leave until he drinks it (literally: without drinking it).
