>>532468075
That's Rin and Alice, the reincarnations of Shion and Mokuren. Rin is 7 and Alice is 16 because it took Shion 9 years to die after Mokuren's death, and Mokuren made him promise not to kill himself.
Rin insists on marrying Alice and comes on to her, and Alice is urged to agree to it because he's "just a kid". Either way Rin keeps it up and ends up impregnating her when he's 16.
>>532469103
I haven't watched that and don't know what you mean.