The Charmian Queen and mother of Lala/Momo/Nana takes half a day to stop by Earth and check on her daughters. Given that she is an attractive female, you can probably guess what happens.
This chapter provides the falling action of the Yami/Darkness arc, as various characters get a breather after all the intense ecchi shenanigans they’d just gone through.
This appears to be a very sexy OVA, maybe the hottest yet. But it also made some head scratching decisions, including some surprising frontal censorship.