No that doesn't happen, for animals its kill or be killed, if the bear was planning on attacking the kid, it would not wait for the kid to turn around. It would not give the kid a chance to retaliate. Especially if the bear is starving, which is implied I think. Dead kid, the end.
Bear should not have been surprised, it has a superior sense of smell, it should've been walking on four legs, only rearing up to strike, not stand and stare and roar at retarded MC like some retarded bear. Damn, why is it so hard to find a good survival manga, it's like trying to find a good survival game. It's not like its that hard to find a proper survival guide, just make up a plot and then guide the MC through survival of various very realistic very dangerous situations such as food poisoning from the water, waste disposal, flu, infected wounds, worn out clothes (trying to replace clothes that get worn out, where does the MC get his clothes? Amazon?), fire(yes, he addressed the problem, but you'd think a few chapters could've been devoted to such an important survival tactic, instead of a few pages.).
Well, if anyone has any suggestions for a good survival manga (no contrived plot, no stupid, oh my god, he survived? HOW? He was lucky? x9, i've seen too many survival manga like that.) feel free to help out a person in need.