俺は悪の戦闘員～女首領の手先になって正義のヒロインをヤる！（Ore wa Aku no Sentouin ~Onna Shuryou no Tesaki ni Natte Seigi no Heroine o Yaru!）

I was just a company man drinking at the bar after work when a beautiful older woman chatted me up.
Next thing I knew, I was the newest recruit in an evil alliance who gets sent on (naughty) missions!

[From DLsite English]