The Reason why Ikuto always passes out when things are getting sexual is that he never got any before he came to the island.
Ikuto will start to use two sword style of fighting
Suzu is Ikuto's sister
Karaage is training Ikuto to be his successor.
Airantō is really The Garden of EdenThe island is a complete paradise with no real troubles or worries. Man and beast can communicate and live in harmony and it's completely isolated from the outside world, except for a chosen few. My theory is that the Sea Dragon God is the flaming sword that God put around Eden after casting man out in Genesis. The rest of the animals were allowed to stay and because of constantly living in Eden they changed to be closer to God's form, more human like as we were created in his image, and that's why they can walk and communicate with each other and humans. The reason why humanity is back on Eden is we are being given a second chance so the Flaming Sword/Sea Dragon, was ordered to allow some people through and it used storms to gain humans for the test subjects in this new experiment. Remember everyone arrives because of some storm or another driving them there. The people there are chosen for their good and kind hearts. Why Eden is not still perfect though is that sin still exist in the world so disease and pain are still in the island, but just to a much smaller degree than the outside world. The people are put onto the island to see if purity of spirit can exist there even if purity of body cannot. The reason all of the men disappeared is that the Flaming Sword/Sea Dragon judged them to be ruining the purity of the island so he had them swept out to sea, and a few years later he brought Ikuto to the island because he is about as innocent and pure of a human as possible. Unfortunately this has backfired a little in that Ikuto is too innocent to participate in sexual escapades to start the next generation of humans. The Flaming Sword/Sea Dragon noticed this and brought in Mei Mei is he thought that Ikuto was not getting it on because of cultural differences not realizing that his own criteria is what is jinixing his attempts at purity.
Makun the genie will play a much, much bigger role in an upcoming story arc.In one of the earlier chapters (the one involving the spirit with a daughter that looked identical to Ayane), Makun is featured amongst the "very powerful entities" on the island, alongside the Southern and Eastern Lords and several silhouetted figures. What what it be like, then, if the cute little genie really cut loose and started abusing his power...?
Ikuto has a weak Anti-Magic fieldThis is why he can touch ghosts, and why Chikage's spell in chapter 22 affected him and Suzu the least. This is also the reason that he was able to escape the Dream World and how it affected him differently. It's not perfect Anti-Magic, but it does give him some resistane to super natural phenomenon or at least mess it up a bit.
The girls' fathers washed up somewhere elseChapter 124 shows Ikuto's father and grandfather searching for Misaki, and very knowledgable with the existence of Airantou. Two men suspciously looks like Machi and Ayane's father Nagamasa and Chikage's father. This means they all survived, but unable to reach the island