Ryusei 流星, the 'falling star', is the far-corner INDIRECT opening: white's second takes the diagonal, black's third settles at the far corner of the 5×5 zone, diagonally two from the centre with one empty between. Theory leans slightly white — the corner stone is solid but a step slower, so black plays the counterpunching style: absorb the first push, answer with the stones you already own. White's fourth here forms a diagonal pair aimed at your corner. Punch back on the correct side: block the end that your corner stone watches, so the block itself becomes a new pair.
Solve the remaining tasks to finish this lesson.