Vocabulary consisting only from characters you are able to read
階級
kaikjuu
class, rank, grademix
守る
mamoru
(1)to protect/to guard/to defend/ (2)to keep (i.e. a promise)/to abide (by the rules)/to observe/to obey/to follow/(P) godan, jlpt3, leda1, verb, vtrans
争う
arasou
(1)to compete, to contest, to contend, (2)to quarrel, to argue, to dispute, to be at variance, to oppose, (3)(usu. in negative form) to deny (e.g. evidence) godan, jlpt3, verb, vintrans
係る
kakawaru
(1)to be the work of, to be the result of, to be done by, (2)to concern, to affect, to involve, to relate to; (3)to be affected, to be influenced, (4)to be concerned with, to have to do with, (5) godan, verb, vintrans
老化
rouka
ageing, aging, senile deteriorationsuru
連想
rensou
association (of ideas), being reminded (of something), suggestionsuru