Sentence:  He had gone into the Japanese navy , had been trained as an officer , had participated in one or two battles - he never went into detail regarding his military experience - and at the age of twenty-five , quite as a bolt out of the blue , he had walked into the mission as if he belonged <WSD>here</WSD> and had become a Christian . 
Meaning of the word marked with <WSD> tags:  in or at this place; where the speaker or writer is