Nagasarete Airantou

They are the fathers, not some boys.

The last page of the chapter where they shown the men, there's was a shadow of a long hair women. In the dream here Suzu's mother was talking about this world or w/e... it was refering as to Airantou and the outside world. So possible the mother didn't die or anything, it was said she was missing. She went to search for the missing men, in other words the missing men who got cast away when the tsunami or storm threw them off the island. Now the men are coming back or are trying to come back and that shadow seems to be Suzu's mother. Well, that might be it in my opinion. The shadow definitely looks of a women.
Someone can correct me but I guess this is what is happening. Soon we'll see the men, fathers back to the island and probably Suzu's mom comes back. Then Ikuto has to make a choice to leave or not, also... the fathers will either be spoiling their daughters to help their romance or be over protective... some plot development there in a way or some gags...
Also, the last thing would be about Ikuto's incarnation or w/e... there's a bit more but how did Keima from TWOG says... "I can see the ending"... in other words, it's coming soon.

well, there's this arc with the sister who my bet that she isn't blood related, that she's a half-yokai and that she's in love with ikuto, that's what i felt the author is gonna do... i don't know if it was predictable but the hints were going that way for what i would like to happen and make interesting.
Then there's the whale, dream boss or the other world... it seems that ikuto is some sort of gate to that world and suzu's mother got involved somehow few times. That's one arc where we would along with the sister arc to get know know more about ikuto, as we kept getting vague hints about his life and existance. Then there's gonna a be another arc with the aliens and the final arc with the dragon, as ikuto being the dragon's friend who went traveling and died... so there's quite a few arc in my opinion to go in order to know more about ikuto. He's still a mystery and in the end, I'd like this manga to go on for another hundredth chapters or so, cause there's so many ways you can make it interesting... there can be more arcs with funny romance comedy too.
Well, this is my own theory to the hints the author might be suggesting. The sister is clear that she's a half yokai cause of the weather and looks like the other half yokai snow girl from the island.... it was pretty obvious.

the sister ain't blood related and she's a half yokai, that's what she wanted to tell him on her birthday date.