Kokoro is carried away by Kotonoha: "Kuyou-kun is taking a bath, don't disturb him."

Kokoro: "That's cunning! Are you going to monopolize Onii-chan?"

Kotonoha speaks in blush: "Why do you say that?"

Kokoro swells out her mildly bulged chest, which had begun to develop for her nine-years-old age: "You attempt to seduce Onii-chan with these…"

Kotonoha is even blusher: "I…I never…attempt to do that…"

Unlike her reserved and shy sister, Kokoro is outgoing and full of energy. So she easily gains an upper hand to tease Kotonoha around, then Manami interferes as a peace-maker.

Qu Yang hears them all: "A happy warm family. That's one thing I dream for. Even for Kokoro and Kotonoha's parents, I will never fail to help her!"

So Qu Yang lives with Kotonoha's family from that day on. The happiest people about this are Kotonoha and Kokoro. Especially the little sister, she "forces" him to play with her every single day, even attempts to seduce him.

Everyday, Kotonoha and Qu Yang move together, stop together, study together, live together…well, "live together" needs discussion.

However, Makoto and Sekai's relationship is deepening day by day. Kotonoha follows them and watches everything, with Qu Yang's company.

This lunchtime, Kotonoha stands inside the door to roof, watches Makoto and Sekai's actions outside the door. Qu Yang stands behind her as usual.

About thirty meters away, Sekai is lying on a davenport, moaning loudly. Her uniform is open and grey-white stripe bra is thrown aside. Makoto is squeezing her right breast by left hand mercilessly, while his right hand clamps her left breast to make her hardened, cherry-like pink nipple on the top even erecter than normal, and sucks it with overly strength, making a lascivious sound.

Sekai: "Ah! Ow…Makoto…don't squeeze so hard…ouch…you're sucking it too strong…" But she is also enjoying what Makoto is doing. Her eyes are closed because of joy, and tears fall from canthus because of pain.

A few minutes later, something even more outrageous happens. Sekai holds the wire entanglements, with Makoto stands behind her, holding her waist. The girl is almost fully nude, only black thighhighs and shoes remaining. Makoto's stick-shaped organ had plugged in her private sector, moves like a piston. Synchronal with Makoto's action, Sekai's body vibrates back and front.

Upon seeing these, Kotonoha can barely stand. Qu Yang tightly holds her hand to keep her from falling in a faint. Kotonoha's heart is suffering from Makoto and Sekai's betrayal, shatters in pieces, then is being cured by Qu Yang's friendly care. This cycle repeats again and again, the gauge is steadily increasing, passed line of second level, 55%...57%...59%...

Makoto and Sekai had experienced climax, now they are lying together on floor.

Sekai: "You are barbarous! Look what you had done!" Her breasts now are covered with scarlet marks left by Makoto's hands: "They are going to ache for hours, and the marks may not recede for days."

Makoto: "You told me to use strength. And you like it don't you?"

Sekai: "How do you feel about me?"

Makoto: "Magnificent."

Sekai: "Even better then Katsura-san? Tell me, you want her more than me right? Especially her breasts, how can such a slender girl like her capable to support such huge objects…"

Makoto: "Kotonoha's are indeed much larger than yours, but she never allows me to touch, at this factor you're much better. Besides, yours are not small after all."

Sekai: "I like what you say. Don't care about her, care about what you can get."

Makoto: "Shall we do it again?"

Sekai: "The first afternoon lesson will begin in ten minutes."

Makoto: "Don't care about lessons, care about what we can do."

Sekai: "That's reasonable." Then there are again moans and various sounds come through.

Kotonoha, grievously hurt by what they did and said, finally speaks in a very low volume: "Saionji-san is the real siren." She's too disappointed of her most-trusted female friend, but although too disappointed of her boyfriend as well, Kotonoha never says anything negative about Makoto.

As they back to classroom, they come cross someone has waited for them for a long time. A petite figure, so petite that can be mistaken for a pupil if not in high school uniform. In other words, if we take Kotonoha as a good example of "overdeveloped", this girl is a good example of "undeveloped".

This pseudo-loli Setsuna Kiyoura, who is also the class-rep of Grade One Class Three and an executive of student council, speaks without emotion, seems someone forgot to program her with some emotions: "You two had already got this close?"

Kotonoha suddenly realizes she is being assisted by Qu Yang to her feet. She immediately breaks off: "Kuyou-kun, this is Kiyoura-san from Class Three…"

Qu Yang calmly answers Setsuna: "I'm Kotonoha's adopted elder brother, so what's the problem?"

Setsuna is still emotionless: "I just wanted to tell you two not to disturb my friend Sekai, but now it's not necessary." She leaves.

Qu Yang: "Really? However this issue is not up to you as you surrendered your feelings to Sekai, my friend. "

Setsuna stops and trembles for a second, then goes on leave: "Whatever, you sister-addicted."