Both brothers keep giving all kind of signals to their mother that there is something wrong, but all she cares about is Rikuto becoming a doctor to take over the father’s hospital and Takuto has to look after Rikuto. Takuto even confronted her and asked if she is paying proper attention, but she didn’t seem to get it. Even his co-workers are thinking that something is happening to Takuto, but the mother still nothing, zero concern from her part.
Finally, revealing to his co-workers and to his friend, it’s actually a step forward to Takuto into accepting the reality and the future. They start t change their attitude towards him, becoming more understanding, however maybe it would’ve been better not to change all of a sudden when it comes to him, but that’s understandable, they don’t know how to react to the sudden news.
It may be just a personal opinion, but they way Mamoru treats Takuto after finding out about the disease, just as the Takuto he always knew it’s better. Rather than having a total change, Mamoru doesn’t want to make Takuto feel vulnerable, but still helps him within the edge of not giving any “because you are having health problems, I’m doing it for you/because you can’t do it for yourself from now on” –vibe.
I’m starting to think that Rikuto knows about Takuto having ALS, but he decided to wait for the older brother to tell when he will be prepared. Because there is the moment when Takuto insisted to give the mother a massage, and Rikuto turned off the TV and let the mother and Takuto alone, seemed like he knew that his brother is trying/wanting to say something to the mother but she still doesn’t get the signs. She needed to hear him spell it all aloud for her to finally get what’s happening. But after revealing to his mother about having ALS, Takuto seemed relived, like something heavy was lifted from his shoulders.