That's high praise, thank you! Morenatsu was the key inspiration which led to Sileo's creation. In an abstract sort of way, Sileo is a big homage to Morenatsu. Without it, Sileo definitely wouldn't exist.
In terms of the nude sprites, the bad news is that Lukas is a ken doll at the moment, and Axel's 'equipment' is little more than uncolored and unapproved lineart. Later on I began insisting that character sprites were fully featured from the get go as that made things easier when the time came to show those characters in the nude, but earlier characters didn't get the same treatment unfortunately.
I can however offer a consolation prize.
1) Lukas' has a large horse cock.
2) Axel has a smaller, human-style uncut penis.
3) One such character that is fully featured but has never been fully nude ingame is Roux. And here he is.