Fetching details from the dictionary...

I; me
oneself
吾こそが正当な後継者だと名乗り出た。
He stepped forward declaring that he was the rightful heir.
吾は古い日本語で自分自身を指す言葉である。
The word 'ware' is an archaic Japanese term referring to oneself.
吾が子の成長を見届けるまでは働き続ける。
I will keep working until I see my child grow up.