Final answer:
The question does not provide enough context to determine why Hachiya is specifically happy, but drawing parallels to similar situations, it is suggested that camaraderie and a sense of accomplishment contribute to such feelings.
Step-by-step explanation:
It is not explicitly clear why Hachiya is happy to see the hospital and his fellow workers because there is insufficient context provided about Hachiya. However, drawing from the text about the fireman, one can infer that the happiness could stem from a sense of relief and camaraderie after surviving a traumatic event.
Similarly, in the extract about Marcus and the dentist arriving at the dog hospital, the sense of happiness could be linked to the completion of a challenging endeavor, returning to a place of familiarity, or feeling a sense of accomplishment. The atmosphere in the hospital and the support from fellow workers are likely significant factors contributing to these feelings of happiness.