This below is really a good 1: I think the implication of this short-term marriage is for an able man, he can take care the life of a single lady/parent as his possibly 2nd wife temporarily, without too much/many consequences/troubles. As well as helping the female for solving certain important problems. Perhaps even the female is a married wife (?)! While her husband being locked in prison! According a movie about Genghis Khan that I watched long time ago. Actually a fairly scientific and reasonable concept and practical!
Just a thought: My guess/hypothesis is we should not underestimate the long term significant impact of the above-mentioned marriage system(s) and the systemic issues. One system could produce many daily news about problems on cheating, family violence, murder, divorce, single parent, homelessness, (il)legal sex industry, drug, corruption, etc. Just unsure whether it is related, closely or not, to the negative growth on total population of the western world which is very much shrinking overall, basically in almost all western countries, including Japan. An issue shouldn't be completely ignored!
This is an aspect that seems to be a key feature among Muslims : the issues of under the belt. There is something about so many virgins for just one guy: - does the guy need to commit suicide to benefit? I mean if the guy just dies of old age, is he excluded from such arrangements? - after these virgins have been "consumated" : what happens to them? - do these virgins agree? is their opinion required ?