消極的だ
My friend is reserved.
私の友達はは消極的です
My friend is reserved when meeting people for the first time.
私の友達は初めて会うは消極的です
My friend is reserved in front of people they are meeting for the first time.
私の友達は初めて会う人たちの前では消極的です
My friend is reserved in front of people they are meeting for the first time at the start of a gathering.
私の友達は初めて会う人たちの前では集まりの初めのうちは消極的です
My friend is more reserved than usual in front of people they are meeting for the first time at the start of a gathering.
私の友達は初めて会う人たちの前では集まりの初めのうちは普段より消極的です