彼は事件の筋を追ってる

N5 彼 kare he N3 事件 jiken incident, case, event N3 筋 suji muscle, line, thread, logic

N3 彼 hi / kare, kano, ka.no he, that, the N4 事 ji, zu / koto, tsuka.u, tsuka.eru matter, thing, fact N3 件 ken / kudan affair, case, matter N1 筋 kin / suji muscle, sinew, tendon N3 追 tsui / o.u chase, drive away, follow

N5 〜ている te iru Indicates ongoing action, continuous state, repeated habit, or resulting condition depending on context N5 〜を o Marks the direct object of an action, appears before the verb, shows what receives the action N5 〜の no Indicates possession, relation between nouns, nominal explanation, or turns a verb into a noun phrase N5 〜は wa Marks the topic of the sentence, indicates what the sentence is about, can contrast with another element, organizes main information