The game starts with Rance going to japan to hit Aroma-hime, nobunaga's sister, but she turns out to be a loli, so he doesn't, but over drinks with nobunaga, nobunaga tells him he's tired of leading the clan, and gives it to Rance.

it's a strategy game where you conquer JAPAN, capturing territories/captains to add to your army, you get an H-scene every time you capture a territory, and also there are a bunch of h-scenes if you max a characters love-meter out (which also causes them to level up/increase stats, an increases Rance's satisfaction which gives a variety of bonuses)

http://alicesoft.wikia.com/wiki/Sengoku_Rance <-- everything you could possibly want to know about the game, down to what units the houses have, whta they do, how the game systems work, etc.

Though I have no idea what context this picture was used in (During their first encounter?).

Japanese homepage: http://www.alicesoft.com/rance7/