Sumomomo, Momomo, Vol. 4

Koushi moves into the Nakajima apartments, his father's reprimand still
ringing in his ears. Though he is less than thrilled with the idea of
becoming a martial artist, Koushi realizes he can't stay indifferent for
long. The Koganei clan is already on the prowl, and a well-aimed poison
ping-pong ball catches Koushi off guard. As the slow-working poison
takes its toll, Koushi despairs. No amount of training can save him
now...but perhaps the Strongest Bride on Earth can?