To, omowazu jigajisan.
He unthinkingly complimented himself.
- to = quotation marker quoting the previous sentence
What decorated his large eyes were long lashes and quite sexy eyelids.
- futae mabuta = eyelids that look Caucasian rather than having the epicanthic fold of standard Asian eyelids, called hitoe mabuta
Caucasian eyelids are considered more attractive than Asian eyelids, so many Asian women (and even some men) these days have plastic surgery to change the appearance of their eyelids. We are supposed to believe that Kouhei has such Caucasian eyelids naturally.
His well-formed lips were plump and looked soft.
Subesube hoppe wa, honnori sakurairo.
His smooth cheeks were blushed with the color of sakura.
Hayaumare no sei ka 165 senchi ni todoku ka todokanai ka no shinchou wa, risou yori hikui monono, sono bun yokei ni puritii-do appu.
Perhaps due to his premature birth, his height of barely 165 centimeters [about 5'6"] was less than his ideal, yet it increased his degree of prettiness.
- todoku ka todokanai ka = lit. "whether it reached or it didn't" or "maybe it reached, maybe it didn't"
This is an idiomatic usage that means "just about" or "barely" or "in the neighborhood of."
"Oh, well."
- i'kka = casual pronunciation of ii ka
The wind of the town, where he stepped out with a light mood, felt good blowing through his hair, and he mused that his mood might also be "pink."
--'Tte, nonki ni omotte ita tokoro e, kushan.
--Just as he was absentmindedly thinking that, he sneezed.
- nonki = "without serious thought"; often used when someone is scatterbrained or carefree
- It is a cultural belief that if you are cold, you automatically (and instantly) sneeze. It also means you are in imminent danger of coming down with a cold/fever.
"Oops... It's probably too cold to be sleeveless."
9-gatsu mo matsu, sorosoro kaze ni aki no nioi ga majitte iru.
The end of September, soon the scent of fall would be in the air.
Zuzu'tto hana o susuri-nagara, kamibukuro no naka kara fuudo-tsuki no jaketto o hipparidashita.
Sniffing, he pulled a hooded jacket from his paper bag.
Kaoru ni niau ka to omotte tsuitsui katte shimatta sore wa, haotte miru to dabudabu de, soryaa Kaoru no hou ga saizu ga ookii kara shou ga nai kedo, yappa chotto shokku ka mo.
He bought it on impulse thinking it would suit Kaoru, but when he tried
putting it on it was too big for him, and though he couldn't help that
Kaoru was larger than he was, it was a bit of a shock.
Kaoru wa otona de, jibun wa kodomo.
Kaoru was an adult, and he was a child.
Sore ga fuku no saizu no sa.
That was the difference between their clothes sizes.
Doushite mo oitsukanai, sa.
A gap that he couldn't overcome, no matter what he did.
"Haa... Munashii kara, yappari yameyou."
"Whew... This is pointless, so I'll just quit."