彼、ちゃんと理由があるはずだと主張した

N5 彼 kare he N3 ちゃんと chanto properly, correctly, carefully N4 理由 riyuu reason, cause N4 はず hazu logical expectation, should be N1 だと dato if it's the case N3 主張 shuchou claim, assertion, insistence

N3 彼 hi / kare, kano, ka.no he, that, the N4 理 ri / kotowari logic, arrangement, reason N3 由 yu, yuu, yui / yoshi, yo.ru wherefore, a reason, c'est pourquoi N4 主 shu, su, shuu / nushi, omo, aruji lord, chief, master N1 張 chou / ha.ru, -ha.ri, -ba.ri lengthen, counter for bows & stringed instruments, stretch

N4 〜はずだ hazu da Indicates logical expectation based on known information, attaches to verb adjective or noun, means should or must be N4 〜し shi Indicates multiple reasons or qualities, connects clauses or adjectives, means besides that, and also N5 〜が ga Marks the grammatical subject, highlights new information, can also show slight contrast in some sentences N5 〜と to Indicates company, quotation, natural condition, complete list, or direct connection between elements N5 〜は wa Marks the topic of the sentence, indicates what the sentence is about, can contrast with another element, organizes main information