彼、心配事が頭の中に溜まっていった

N5 彼 kare he N4 心配 shinpai worry, concern, anxiety N4 事 koto thing, matter, fact, event N5 頭 atama head N5 中 naka inside / middle

N3 彼 hi / kare, kano, ka.no he, that, the N4 心 shin / kokoro, -gokoro heart, mind, spirit N3 配 hai / kuba.ru distribute, spouse, exile N4 事 ji, zu / koto, tsuka.u, tsuka.eru matter, thing, fact N3 頭 tou, zu, to / atama, kashira, -gashira, kaburi head, counter for large animals, tête N5 中 chuu / naka, uchi, ata.ru in, inside, middle

N5 〜ている te iru Indicates ongoing action, continuous state, repeated habit, or resulting condition depending on context N5 〜が ga Marks the grammatical subject, highlights new information, can also show slight contrast in some sentences N5 〜に ni Indicates destination, target, arrival point, specific time, or person receiving an action N5 〜の no Indicates possession, relation between nouns, nominal explanation, or turns a verb into a noun phrase