na-adjective
reflective; introspective
Describes a person, mood, or attitude that looks inward and examines one's own thoughts and feelings.
彼はとても内省的な性格だ。
He has a very introspective personality.
内省的な気分になって、自分の行動を振り返
I became reflective and looked back on my own actions.
From 内省 (ないせい, 'self-reflection') + 的 (てき, '-ive'). The exact historical derivation is uncertain, but the components are transparent.