Quite convenient how everyone who donated blood had the same blood type as the guy who needed it… seems a bit too convenient…
They don't need to. If he has A, he can accept from O and A blood types. If he has B, he can accept from O and B blood types. Lastly, if he has the rare-ish blood type AB, he can accept from O, A, and B but he can only donate blood to someone who also has blood type AB. If he has O though, yeah everyone also has to have blood type O to donate to him in that case.
Lol no it's pretty basic biology stuff ^^;
One thing I forgot to mention though, is that O is the most common blood type that there is so even if he is blood type O (and therefore can only accept blood from O donors) there's still a higher chance that others are also blood type O than any other type. So it's all to say that it's not that unrealistic that he can receive blood from so many people.
Can someone please post the rest of chapter 105 TT^TT